diff --git a/rpc/core/mempool.go b/rpc/core/mempool.go
index dfe841365..f78f9d8b0 100644
--- a/rpc/core/mempool.go
+++ b/rpc/core/mempool.go
@@ -18,7 +18,7 @@ func BroadcastTxAsync(tx types.Tx) (*ctypes.ResultBroadcastTx, error) {
 	if err != nil {
 		return nil, fmt.Errorf("Error broadcasting transaction: %v", err)
 	}
-	return &ctypes.ResultBroadcastTx{}, nil
+	return &ctypes.ResultBroadcastTx{TxID: tx.Hash()}, nil
 }
 
 // Returns with the response from CheckTx
@@ -36,6 +36,7 @@ func BroadcastTxSync(tx types.Tx) (*ctypes.ResultBroadcastTx, error) {
 		Code: r.Code,
 		Data: r.Data,
 		Log:  r.Log,
+		TxID: tx.Hash(),
 	}, nil
 }
 
@@ -67,6 +68,7 @@ func BroadcastTxCommit(tx types.Tx) (*ctypes.ResultBroadcastTxCommit, error) {
 		return &ctypes.ResultBroadcastTxCommit{
 			CheckTx:   checkTxR,
 			DeliverTx: nil,
+			TxID:      tx.Hash(),
 		}, nil
 	}
 
@@ -86,12 +88,14 @@ func BroadcastTxCommit(tx types.Tx) (*ctypes.ResultBroadcastTxCommit, error) {
 		return &ctypes.ResultBroadcastTxCommit{
 			CheckTx:   checkTxR,
 			DeliverTx: deliverTxR,
+			TxID:      tx.Hash(),
 		}, nil
 	case <-timer.C:
 		log.Error("failed to include tx")
 		return &ctypes.ResultBroadcastTxCommit{
 			CheckTx:   checkTxR,
 			DeliverTx: nil,
+			TxID:      tx.Hash(),
 		}, fmt.Errorf("Timed out waiting for transaction to be included in a block")
 	}
 
diff --git a/rpc/core/routes.go b/rpc/core/routes.go
index e79fb0299..8de828826 100644
--- a/rpc/core/routes.go
+++ b/rpc/core/routes.go
@@ -1,12 +1,9 @@
 package core
 
 import (
-	"strings"
-
 	rpc "github.com/tendermint/go-rpc/server"
 	"github.com/tendermint/go-rpc/types"
 	ctypes "github.com/tendermint/tendermint/rpc/core/types"
-	"github.com/tendermint/tendermint/types"
 )
 
 // TODO: better system than "unsafe" prefix
@@ -22,11 +19,11 @@ var Routes = map[string]*rpc.RPCFunc{
 	"genesis":              rpc.NewRPCFunc(GenesisResult, ""),
 	"block":                rpc.NewRPCFunc(BlockResult, "height"),
 	"commit":               rpc.NewRPCFunc(CommitResult, "height"),
+	"tx":                   rpc.NewRPCFunc(TxResult, "hash"),
 	"validators":           rpc.NewRPCFunc(ValidatorsResult, ""),
 	"dump_consensus_state": rpc.NewRPCFunc(DumpConsensusStateResult, ""),
 	"unconfirmed_txs":      rpc.NewRPCFunc(UnconfirmedTxsResult, ""),
 	"num_unconfirmed_txs":  rpc.NewRPCFunc(NumUnconfirmedTxsResult, ""),
-	"tx": rpc.NewRPCFunc(Tx, "hash"),
 
 	// broadcast API
 	"broadcast_tx_commit": rpc.NewRPCFunc(BroadcastTxCommitResult, "tx"),
@@ -103,13 +100,8 @@ func NumUnconfirmedTxsResult() (ctypes.TMResult, error) {
 // Tx allow user to query the transaction results. `nil` could mean the
 // transaction is in the mempool, invalidated, or was not send in the first
 // place.
-func Tx(hash string) (ctypes.TMResult, error) {
-	r, err := txIndexer.Tx(strings.ToLower(hash))
-	// nil-pointer interface values are forbidden in go-rpc
-	if r == (*types.TxResult)(nil) {
-		return nil, err
-	}
-	return r, err
+func TxResult(hash []byte) (ctypes.TMResult, error) {
+	return Tx(hash)
 }
 
 func BroadcastTxCommitResult(tx []byte) (ctypes.TMResult, error) {
diff --git a/rpc/core/tx.go b/rpc/core/tx.go
new file mode 100644
index 000000000..bffeced7c
--- /dev/null
+++ b/rpc/core/tx.go
@@ -0,0 +1,13 @@
+package core
+
+import (
+	ctypes "github.com/tendermint/tendermint/rpc/core/types"
+)
+
+func Tx(hash []byte) (*ctypes.ResultTx, error) {
+	r, err := txIndexer.Tx(hash)
+	if err != nil {
+		return nil, err
+	}
+	return &ctypes.ResultTx{*r}, nil
+}
diff --git a/rpc/core/types/responses.go b/rpc/core/types/responses.go
index 908a33f19..2ec762e36 100644
--- a/rpc/core/types/responses.go
+++ b/rpc/core/types/responses.go
@@ -67,11 +67,18 @@ type ResultBroadcastTx struct {
 	Code abci.CodeType `json:"code"`
 	Data []byte        `json:"data"`
 	Log  string        `json:"log"`
+
+	TxID []byte `json:"tx_id"`
 }
 
 type ResultBroadcastTxCommit struct {
 	CheckTx   *abci.ResponseCheckTx   `json:"check_tx"`
 	DeliverTx *abci.ResponseDeliverTx `json:"deliver_tx"`
+	TxID      []byte                  `json:"tx_id"`
+}
+
+type ResultTx struct {
+	types.TxResult
 }
 
 type ResultUnconfirmedTxs struct {
@@ -164,7 +171,7 @@ var _ = wire.RegisterInterface(
 	wire.ConcreteType{&ResultDumpConsensusState{}, ResultTypeDumpConsensusState},
 	wire.ConcreteType{&ResultBroadcastTx{}, ResultTypeBroadcastTx},
 	wire.ConcreteType{&ResultBroadcastTxCommit{}, ResultTypeBroadcastTxCommit},
-	wire.ConcreteType{&types.TxResult{}, ResultTypeTx},
+	wire.ConcreteType{&ResultTx{}, ResultTypeTx},
 	wire.ConcreteType{&ResultUnconfirmedTxs{}, ResultTypeUnconfirmedTxs},
 	wire.ConcreteType{&ResultSubscribe{}, ResultTypeSubscribe},
 	wire.ConcreteType{&ResultUnsubscribe{}, ResultTypeUnsubscribe},
diff --git a/state/execution.go b/state/execution.go
index 5f0df6133..545225be1 100644
--- a/state/execution.go
+++ b/state/execution.go
@@ -1,7 +1,6 @@
 package state
 
 import (
-	"encoding/hex"
 	"errors"
 	"fmt"
 
@@ -246,7 +245,7 @@ func (s *State) ApplyBlock(eventCache types.Fireable, proxyAppConn proxy.AppConn
 		if r != nil {
 			tx := block.Txs[i]
 			// dd2e325f79f7e5f77788759d278c1d4b370c842e => {"height":2405, "index":0, ...}
-			batch.Index(hex.EncodeToString(tx.Hash()), *r)
+			batch.Index(tx.Hash(), *r)
 		}
 	}
 	s.TxIndexer.Batch(batch)
diff --git a/state/tx/indexer.go b/state/tx/indexer.go
index 759f141ae..be7f304c4 100644
--- a/state/tx/indexer.go
+++ b/state/tx/indexer.go
@@ -17,5 +17,5 @@ type Indexer interface {
 
 	// Tx returns specified transaction or nil if the transaction is not indexed
 	// or stored.
-	Tx(hash string) (*types.TxResult, error)
+	Tx(hash []byte) (*types.TxResult, error)
 }
diff --git a/state/tx/indexer/batch.go b/state/tx/indexer/batch.go
index 3c64c8869..78137f598 100644
--- a/state/tx/indexer/batch.go
+++ b/state/tx/indexer/batch.go
@@ -18,11 +18,11 @@ func NewBatch() *Batch {
 }
 
 // Index adds or updates entry for the given hash.
-func (b *Batch) Index(hash string, result types.TxResult) error {
-	if hash == "" {
+func (b *Batch) Index(hash []byte, result types.TxResult) error {
+	if len(hash) == 0 {
 		return ErrorEmptyHash
 	}
-	b.Ops[hash] = result
+	b.Ops[string(hash)] = result
 	return nil
 }
 
diff --git a/state/tx/indexer/kv.go b/state/tx/indexer/kv.go
index 0c86d0a35..4f6fb3581 100644
--- a/state/tx/indexer/kv.go
+++ b/state/tx/indexer/kv.go
@@ -22,12 +22,12 @@ func NewKV(store db.DB) *KV {
 
 // Tx gets transaction from the KV storage and returns it or nil if the
 // transaction is not found.
-func (indexer *KV) Tx(hash string) (*types.TxResult, error) {
-	if hash == "" {
+func (indexer *KV) Tx(hash []byte) (*types.TxResult, error) {
+	if len(hash) == 0 {
 		return nil, ErrorEmptyHash
 	}
 
-	rawBytes := indexer.store.Get([]byte(hash))
+	rawBytes := indexer.store.Get(hash)
 	if rawBytes == nil {
 		return nil, nil
 	}
diff --git a/state/tx/indexer/kv_test.go b/state/tx/indexer/kv_test.go
index 0e3b0a7d7..c797151af 100644
--- a/state/tx/indexer/kv_test.go
+++ b/state/tx/indexer/kv_test.go
@@ -18,7 +18,7 @@ func TestKVIndex(t *testing.T) {
 
 	tx := types.Tx("HELLO WORLD")
 	txResult := &types.TxResult{1, 1, abci.ResponseDeliverTx{Data: []byte{0}, Code: abci.CodeType_OK, Log: ""}}
-	hash := string(tx.Hash())
+	hash := tx.Hash()
 
 	batch := NewBatch()
 	batch.Index(hash, *txResult)
@@ -44,7 +44,7 @@ func benchmarkKVIndex(txsCount int, b *testing.B) {
 
 	batch := NewBatch()
 	for i := 0; i < txsCount; i++ {
-		batch.Index(fmt.Sprintf("hash%v", i), *txResult)
+		batch.Index([]byte(fmt.Sprintf("hash%v", i)), *txResult)
 	}
 
 	b.ResetTimer()
diff --git a/state/tx/indexer/null.go b/state/tx/indexer/null.go
index c9df50edb..a322602d0 100644
--- a/state/tx/indexer/null.go
+++ b/state/tx/indexer/null.go
@@ -9,8 +9,8 @@ import (
 type Null struct{}
 
 // Tx panics.
-func (indexer *Null) Tx(hash string) (*types.TxResult, error) {
-	return nil, errors.New("Indexing is disabled (set `tx_indexer=kv` in config)")
+func (indexer *Null) Tx(hash []byte) (*types.TxResult, error) {
+	return nil, errors.New(`Indexing is disabled (set 'tx_indexer = "kv"' in config)`)
 }
 
 // Batch returns nil.