diff --git a/bcm/blockchain.go b/bcm/blockchain.go
index 5c4b59d06..28fde43fc 100644
--- a/bcm/blockchain.go
+++ b/bcm/blockchain.go
@@ -183,7 +183,7 @@ func (bc *Blockchain) GenesisDoc() genesis.GenesisDoc {
 }
 
 func (bc *Blockchain) ChainID() string {
-	return bc.genesisDoc.ChainID()
+	return bc.genesisDoc.GetChainID()
 }
 
 func (bc *Blockchain) LastBlockHeight() uint64 {
diff --git a/cmd/burrow/commands/config_options.go b/cmd/burrow/commands/config_options.go
index a840711a2..5171c9cd4 100644
--- a/cmd/burrow/commands/config_options.go
+++ b/cmd/burrow/commands/config_options.go
@@ -115,8 +115,8 @@ func (opts *configOptions) obtainBurrowConfig() (*config.BurrowConfig, error) {
 	}
 	if *opts.initMonikerOpt == "" {
 		chainIDHeader := ""
-		if conf.GenesisDoc != nil && conf.GenesisDoc.ChainID() != "" {
-			chainIDHeader = conf.GenesisDoc.ChainID() + "_"
+		if conf.GenesisDoc != nil && conf.GenesisDoc.GetChainID() != "" {
+			chainIDHeader = conf.GenesisDoc.GetChainID() + "_"
 		}
 		if conf.ValidatorAddress != nil {
 			// Set a default moniker... since we can at this stage of config completion and it is required for start
diff --git a/config/config.go b/config/config.go
index 9cb6e1746..421a8f75e 100644
--- a/config/config.go
+++ b/config/config.go
@@ -3,6 +3,7 @@ package config
 import (
 	"fmt"
 
+	"github.com/alecthomas/jsonschema"
 	"github.com/hyperledger/burrow/config/source"
 	"github.com/hyperledger/burrow/consensus/tendermint"
 	"github.com/hyperledger/burrow/crypto"
@@ -32,6 +33,8 @@ type BurrowConfig struct {
 	Logging    *logconfig.LoggingConfig           `json:",omitempty" toml:",omitempty"`
 }
 
+var burrowConfigSchema = jsonschema.Reflect(&BurrowConfig{})
+
 func DefaultBurrowConfig() *BurrowConfig {
 	return &BurrowConfig{
 		BurrowDir:  ".burrow",
diff --git a/config/config_test.go b/config/config_test.go
index 16a2d9f0a..2569f9a72 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -1,10 +1,11 @@
 package config
 
 import (
-	"fmt"
 	"testing"
 
+	"github.com/hyperledger/burrow/config/source"
 	"github.com/hyperledger/burrow/genesis"
+	"github.com/stretchr/testify/require"
 )
 
 func TestBurrowConfigSerialise(t *testing.T) {
@@ -13,5 +14,9 @@ func TestBurrowConfigSerialise(t *testing.T) {
 			ChainName: "Foo",
 		},
 	}
-	fmt.Println(conf.JSONString())
+	confOut := new(BurrowConfig)
+	jsonString := conf.JSONString()
+	err := source.FromJSONString(jsonString, confOut)
+	require.NoError(t, err)
+	require.Equal(t, jsonString, confOut.JSONString())
 }
diff --git a/consensus/tendermint/tendermint.go b/consensus/tendermint/tendermint.go
index d31acf0ce..512a57a10 100644
--- a/consensus/tendermint/tendermint.go
+++ b/consensus/tendermint/tendermint.go
@@ -102,7 +102,7 @@ func DeriveGenesisDoc(burrowGenesisDoc *genesis.GenesisDoc, appHash []byte) *tmT
 	consensusParams.Block.TimeIotaMs = 1
 
 	return &tmTypes.GenesisDoc{
-		ChainID:         burrowGenesisDoc.ChainID(),
+		ChainID:         burrowGenesisDoc.GetChainID(),
 		GenesisTime:     burrowGenesisDoc.GenesisTime,
 		Validators:      validators,
 		AppHash:         appHash,
diff --git a/execution/exec/stream_event_test.go b/execution/exec/stream_event_test.go
index b55fd3134..c37790bb9 100644
--- a/execution/exec/stream_event_test.go
+++ b/execution/exec/stream_event_test.go
@@ -17,7 +17,7 @@ import (
 var genesisDoc, accounts, _ = genesis.NewDeterministicGenesis(345234523).GenesisDoc(10, 0)
 
 func TestTxExecution(t *testing.T) {
-	txe := NewTxExecution(txs.Enclose(genesisDoc.ChainID(), newCallTx(0, 1)))
+	txe := NewTxExecution(txs.Enclose(genesisDoc.GetChainID(), newCallTx(0, 1)))
 
 	stack := new(TxStack)
 	var txeOut *TxExecution
@@ -38,7 +38,7 @@ func TestConsumeBlockExecution(t *testing.T) {
 	height := int64(234242)
 	be := &BlockExecution{
 		Header: &tmproto.Header{
-			ChainID: genesisDoc.ChainID(),
+			ChainID: genesisDoc.GetChainID(),
 			AppHash: crypto.Keccak256([]byte("hashily")),
 			Time:    time.Now(),
 			Height:  height,
@@ -46,9 +46,9 @@ func TestConsumeBlockExecution(t *testing.T) {
 		Height: uint64(height),
 	}
 	be.AppendTxs(
-		NewTxExecution(txs.Enclose(genesisDoc.ChainID(), newCallTx(0, 3))),
-		NewTxExecution(txs.Enclose(genesisDoc.ChainID(), newCallTx(0, 2))),
-		NewTxExecution(txs.Enclose(genesisDoc.ChainID(), newCallTx(2, 1))),
+		NewTxExecution(txs.Enclose(genesisDoc.GetChainID(), newCallTx(0, 3))),
+		NewTxExecution(txs.Enclose(genesisDoc.GetChainID(), newCallTx(0, 2))),
+		NewTxExecution(txs.Enclose(genesisDoc.GetChainID(), newCallTx(2, 1))),
 	)
 
 	stack := NewBlockAccumulator()
diff --git a/execution/execution.go b/execution/execution.go
index ff1023603..e5ddd16f7 100644
--- a/execution/execution.go
+++ b/execution/execution.go
@@ -97,7 +97,7 @@ type Params struct {
 
 func ParamsFromGenesis(genesisDoc *genesis.GenesisDoc) Params {
 	return Params{
-		ChainID:           genesisDoc.ChainID(),
+		ChainID:           genesisDoc.GetChainID(),
 		ProposalThreshold: genesisDoc.Params.ProposalThreshold,
 	}
 }
diff --git a/execution/execution_test.go b/execution/execution_test.go
index 3902d9bcf..7954998c5 100644
--- a/execution/execution_test.go
+++ b/execution/execution_test.go
@@ -53,7 +53,7 @@ var logger = logging.NewNoopLogger()
 var deterministicGenesis = genesis.NewDeterministicGenesis(34059836243380576)
 var testGenesisDoc, testPrivAccounts, _ = deterministicGenesis.
 	GenesisDoc(3, 1)
-var testChainID = testGenesisDoc.ChainID()
+var testChainID = testGenesisDoc.GetChainID()
 
 func TestSendFails(t *testing.T) {
 	stateDB, err := dbm.NewDB("state", dbBackend, dbDir)
diff --git a/genesis/genesis.go b/genesis/genesis.go
index 8255ff1b6..387d78c7e 100644
--- a/genesis/genesis.go
+++ b/genesis/genesis.go
@@ -54,17 +54,18 @@ type params struct {
 }
 
 type GenesisDoc struct {
-	GenesisTime       time.Time
-	ChainName         string
-	AppHash           binary.HexBytes `json:",omitempty" toml:",omitempty"`
-	Params            params          `json:",omitempty" toml:",omitempty"`
-	Salt              []byte          `json:",omitempty" toml:",omitempty"`
+	GenesisTime time.Time
+	ChainName   string
+	// Ordinarily we derive this from the genesis hash but to support explicit Ethereum ChainID it may be set
+	ChainID           string `json:",omitempty" toml:",omitempty"`
+	AppHash           binary.HexBytes
+	Params            params `json:",omitempty" toml:",omitempty"`
+	Salt              []byte `json:",omitempty" toml:",omitempty"`
 	GlobalPermissions permission.AccountPermissions
 	Accounts          []Account
 	Validators        []Validator
 	// memo
-	hash    []byte
-	chainID string
+	hash []byte
 }
 
 func (genesisDoc *GenesisDoc) GlobalPermissionsAccount() *acm.Account {
@@ -115,11 +116,11 @@ func (genesisDoc *GenesisDoc) ShortHash() []byte {
 	return genesisDoc.Hash()[:ShortHashSuffixBytes]
 }
 
-func (genesisDoc *GenesisDoc) ChainID() string {
-	if genesisDoc.chainID == "" {
-		genesisDoc.chainID = fmt.Sprintf("%s-%X", genesisDoc.ChainName, genesisDoc.ShortHash())
+func (genesisDoc *GenesisDoc) GetChainID() string {
+	if genesisDoc.ChainID == "" {
+		genesisDoc.ChainID = fmt.Sprintf("%s-%X", genesisDoc.ChainName, genesisDoc.ShortHash())
 	}
-	return genesisDoc.chainID
+	return genesisDoc.ChainID
 }
 
 //------------------------------------------------------------
diff --git a/integration/governance/governance_test.go b/integration/governance/governance_test.go
index a0fdca0cb..ff6f4fc97 100644
--- a/integration/governance/governance_test.go
+++ b/integration/governance/governance_test.go
@@ -226,12 +226,12 @@ func TestGovernance(t *testing.T) {
 			})
 
 			setSequence(t, qcli, tx)
-			_, err := localSignAndBroadcastSync(t, tcli1, genesisDoc.ChainID(), genesisAccounts[0], tx)
+			_, err := localSignAndBroadcastSync(t, tcli1, genesisDoc.GetChainID(), genesisAccounts[0], tx)
 			require.NoError(t, err)
 
 			// Make it a different Tx hash so it can enter cache but keep sequence number
 			tx.AccountUpdates[0].Amounts = balance.New().Power(power).Native(1)
-			_, err = localSignAndBroadcastSync(t, tcli2, genesisDoc.ChainID(), genesisAccounts[0], tx)
+			_, err = localSignAndBroadcastSync(t, tcli2, genesisDoc.GetChainID(), genesisAccounts[0], tx)
 			require.Error(t, err)
 			assert.Contains(t, err.Error(), "invalid sequence")
 		})
diff --git a/integration/rpcinfo/info_server_test.go b/integration/rpcinfo/info_server_test.go
index de6051f35..1c216fbd9 100644
--- a/integration/rpcinfo/info_server_test.go
+++ b/integration/rpcinfo/info_server_test.go
@@ -54,7 +54,7 @@ func TestInfoServer(t *testing.T) {
 				resp, err := infoclient.Status(rpcClient)
 				require.NoError(t, err)
 				assert.Contains(t, resp.GetNodeInfo().GetMoniker(), "node")
-				assert.Equal(t, rpctest.GenesisDoc.ChainID(), resp.NodeInfo.Network,
+				assert.Equal(t, rpctest.GenesisDoc.GetChainID(), resp.NodeInfo.Network,
 					"ChainID should match NodeInfo.Network")
 			})
 
diff --git a/integration/rpcquery/query_server_test.go b/integration/rpcquery/query_server_test.go
index 5bf6e1fee..4914c2ad1 100644
--- a/integration/rpcquery/query_server_test.go
+++ b/integration/rpcquery/query_server_test.go
@@ -31,7 +31,7 @@ func TestQueryServer(t *testing.T) {
 		status, err := cli.Status(context.Background(), &rpcquery.StatusParam{})
 		require.NoError(t, err)
 		assert.Equal(t, rpctest.PrivateAccounts[0].GetPublicKey(), status.ValidatorInfo.PublicKey)
-		assert.Equal(t, rpctest.GenesisDoc.ChainID(), status.ChainID)
+		assert.Equal(t, rpctest.GenesisDoc.GetChainID(), status.ChainID)
 		for i := 0; i < 3; i++ {
 			// Unless we get lucky this is an error
 			_, err = cli.Status(context.Background(), &rpcquery.StatusParam{
diff --git a/integration/rpctest/helpers.go b/integration/rpctest/helpers.go
index d25f4a260..dc9064a58 100644
--- a/integration/rpctest/helpers.go
+++ b/integration/rpctest/helpers.go
@@ -154,7 +154,7 @@ func MakeDefaultCallTx(t *testing.T, client rpc.Client, addr *crypto.Address, co
 	fee uint64) *txs.Envelope {
 	sequence := GetSequence(t, client, PrivateAccounts[0].GetAddress())
 	tx := payload.NewCallTxWithSequence(PrivateAccounts[0].GetPublicKey(), addr, code, amt, gasLim, fee, sequence+1)
-	txEnv := txs.Enclose(GenesisDoc.ChainID(), tx)
+	txEnv := txs.Enclose(GenesisDoc.GetChainID(), tx)
 	require.NoError(t, txEnv.Sign(PrivateAccounts[0]))
 	return txEnv
 }
diff --git a/integration/rpctransact/transact_server_test.go b/integration/rpctransact/transact_server_test.go
index a66d77c13..826a4cdef 100644
--- a/integration/rpctransact/transact_server_test.go
+++ b/integration/rpctransact/transact_server_test.go
@@ -62,7 +62,7 @@ func TestTransactServer(t *testing.T) {
 		})
 		require.NoError(t, err)
 		amount := uint64(2123)
-		txEnv := txs.Enclose(rpctest.GenesisDoc.ChainID(), &payload.SendTx{
+		txEnv := txs.Enclose(rpctest.GenesisDoc.GetChainID(), &payload.SendTx{
 			Inputs: []*payload.TxInput{{
 				Address:  inputAddress,
 				Sequence: acc.Sequence + 1,
@@ -120,7 +120,7 @@ func TestTransactServer(t *testing.T) {
 		// We should see the sign bytes embedded
 		if !assert.Contains(t, string(bs), fmt.Sprintf("{\"ChainID\":\"%s\",\"Type\":\"CallTx\","+
 			"\"Payload\":{\"Input\":{\"Address\":\"E80BB91C2F0F4C3C39FC53E89BF8416B219BE6E4\",\"Amount\":230},"+
-			"\"Data\":\"0203060403\"}}", rpctest.GenesisDoc.ChainID())) {
+			"\"Data\":\"0203060403\"}}", rpctest.GenesisDoc.GetChainID())) {
 			fmt.Println(string(bs))
 		}
 	})
diff --git a/rpc/web3/eth_service.go b/rpc/web3/eth_service.go
index 5ae15e8d3..75362739e 100644
--- a/rpc/web3/eth_service.go
+++ b/rpc/web3/eth_service.go
@@ -45,6 +45,7 @@ type EthService struct {
 	keyClient  keys.KeyClient
 	keyStore   *keys.FilesystemKeyStore
 	config     *tmConfig.Config
+	chainID    *big.Int
 	logger     *logging.Logger
 }
 
@@ -63,16 +64,18 @@ func NewEthService(
 	keyClient := keys.NewLocalKeyClient(keyStore, logger)
 
 	return &EthService{
-		accounts,
-		events,
-		blockchain,
-		validators,
-		nodeView,
-		trans,
-		keyClient,
-		keyStore,
-		tmConfig.DefaultConfig(),
-		logger,
+		accounts:   accounts,
+		events:     events,
+		blockchain: blockchain,
+		validators: validators,
+		nodeView:   nodeView,
+		trans:      trans,
+		keyClient:  keyClient,
+		keyStore:   keyStore,
+		config:     tmConfig.DefaultConfig(),
+		// Ethereum expects ChainID to be an integer value
+		chainID: crypto.GetEthChainID(blockchain.ChainID()),
+		logger:  logger,
 	}
 }
 
@@ -119,7 +122,7 @@ func (srv *EthService) NetPeerCount() (*NetPeerCountResult, error) {
 // this is typically a small int (where 1 == Ethereum mainnet)
 func (srv *EthService) NetVersion() (*NetVersionResult, error) {
 	return &NetVersionResult{
-		ChainID: crypto.GetEthChainID(srv.blockchain.ChainID()).String(),
+		ChainID: HexEncoder.BigInt(srv.chainID),
 	}, nil
 }
 
@@ -133,7 +136,7 @@ func (srv *EthService) EthProtocolVersion() (*EthProtocolVersionResult, error) {
 // EthChainId returns the chainID
 func (srv *EthService) EthChainId() (*EthChainIdResult, error) {
 	return &EthChainIdResult{
-		ChainId: srv.blockchain.ChainID(),
+		ChainId: HexEncoder.BigInt(srv.chainID),
 	}, nil
 }
 
@@ -568,7 +571,7 @@ func (srv *EthService) EthSendRawTransaction(req *EthSendRawTransactionParams) (
 		return nil, d.Err()
 	}
 
-	rawTx := txs.NewEthRawTx(srv.blockchain.ChainID())
+	rawTx := txs.NewEthRawTx(srv.chainID)
 	err := rlp.Decode(data, rawTx)
 	if err != nil {
 		return nil, err
diff --git a/rpc/web3/eth_service_test.go b/rpc/web3/eth_service_test.go
index e8bd75c2b..e3881f9cb 100644
--- a/rpc/web3/eth_service_test.go
+++ b/rpc/web3/eth_service_test.go
@@ -8,10 +8,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/hyperledger/burrow/rpc/web3"
-	"github.com/hyperledger/burrow/txs"
-	"github.com/hyperledger/burrow/txs/payload"
-
 	"github.com/hyperledger/burrow/acm/balance"
 	"github.com/hyperledger/burrow/crypto"
 	"github.com/hyperledger/burrow/execution/evm/abi"
@@ -20,17 +16,23 @@ import (
 	"github.com/hyperledger/burrow/logging"
 	"github.com/hyperledger/burrow/project"
 	"github.com/hyperledger/burrow/rpc"
+	"github.com/hyperledger/burrow/rpc/web3"
+	"github.com/hyperledger/burrow/txs"
+	"github.com/hyperledger/burrow/txs/payload"
 	"github.com/stretchr/testify/require"
 )
 
 var d = new(web3.HexDecoder).Must()
 
+// Check we can force set a decimal ChainID
+const chainID = "15321"
+
 func TestWeb3Service(t *testing.T) {
 	ctx := context.Background()
 	genesisAccounts := integration.MakePrivateAccounts("burrow", 1)
 	genesisAccounts = append(genesisAccounts, integration.MakeEthereumAccounts("ethereum", 3)...)
 	genesisDoc := integration.TestGenesisDoc(genesisAccounts, 0)
-
+	genesisDoc.ChainID = chainID
 	config, _ := integration.NewTestConfig(genesisDoc)
 	logger := logging.NewNoopLogger()
 	kern, err := integration.TestKernel(genesisAccounts[0], genesisAccounts, config)
@@ -91,7 +93,7 @@ func TestWeb3Service(t *testing.T) {
 		t.Run("NetVersion", func(t *testing.T) {
 			result, err := eth.NetVersion()
 			require.NoError(t, err)
-			require.Equal(t, crypto.GetEthChainID(genesisDoc.ChainID()).String(), result.ChainID)
+			require.Equal(t, web3.HexEncoder.BigInt(crypto.GetEthChainID(genesisDoc.GetChainID())), result.ChainID)
 		})
 
 		t.Run("EthProtocolVersion", func(t *testing.T) {
@@ -104,7 +106,7 @@ func TestWeb3Service(t *testing.T) {
 			result, err := eth.EthChainId()
 			require.NoError(t, err)
 			doc := config.GenesisDoc
-			require.Equal(t, doc.ChainID(), result.ChainId)
+			require.Equal(t, web3.HexEncoder.BigInt(crypto.GetEthChainID(doc.GetChainID())), result.ChainId)
 		})
 	})
 
@@ -118,7 +120,7 @@ func TestWeb3Service(t *testing.T) {
 		before := acc.GetBalance()
 
 		t.Run("EthSendRawTransaction", func(t *testing.T) {
-			txEnv := txs.Enclose(genesisDoc.ChainID(), &payload.CallTx{
+			txEnv := txs.Enclose(chainID, &payload.CallTx{
 				Input: &payload.TxInput{
 					Address:  sender.GetAddress(),
 					Amount:   1,
diff --git a/rpc/web3/hex.go b/rpc/web3/hex.go
index 4822ce0a8..24bbe6792 100644
--- a/rpc/web3/hex.go
+++ b/rpc/web3/hex.go
@@ -99,7 +99,7 @@ func (e *hexEncoder) BytesTrim(bs []byte) string {
 	return "0x" + str
 }
 
-func (e *hexEncoder) BigInt(x big.Int) string {
+func (e *hexEncoder) BigInt(x *big.Int) string {
 	return e.BytesTrim(x.Bytes())
 }
 
diff --git a/txs/ethereum_tx.go b/txs/ethereum_tx.go
index 070a22929..79ca23918 100644
--- a/txs/ethereum_tx.go
+++ b/txs/ethereum_tx.go
@@ -26,8 +26,8 @@ type EthRawTx struct {
 	chainID *big.Int
 }
 
-func NewEthRawTx(chainID string) *EthRawTx {
-	return &EthRawTx{chainID: crypto.GetEthChainID(chainID)}
+func NewEthRawTx(chainID *big.Int) *EthRawTx {
+	return &EthRawTx{chainID: chainID}
 }
 
 func EthRawTxFromEnvelope(txEnv *Envelope) (*EthRawTx, error) {