diff --git a/docs/tendermint-core/using-tendermint.md b/docs/tendermint-core/using-tendermint.md
index bbcdd0370..4b8a26bad 100644
--- a/docs/tendermint-core/using-tendermint.md
+++ b/docs/tendermint-core/using-tendermint.md
@@ -185,51 +185,65 @@ the argument name and use `_` as a placeholder.
 
 ### Formatting
 
-The following nuances when sending/formatting transactions should be
-taken into account:
+When sending transactions to the RPC interface, the following formatting rules
+must be followed:
 
-With `GET`:
+Using `GET` (with parameters in the URL):
 
-To send a UTF8 string byte array, quote the value of the tx parameter:
+To send a UTF8 string as transaction data, enclose the value of the `tx`
+parameter in double quotes:
 
 ```sh
 curl 'http://localhost:26657/broadcast_tx_commit?tx="hello"'
 ```
 
-which sends a 5 byte transaction: "h e l l o" \[68 65 6c 6c 6f\].
+which sends a 5-byte transaction: "h e l l o" \[68 65 6c 6c 6f\].
 
-Note the URL must be wrapped with single quotes, else bash will ignore
-the double quotes. To avoid the single quotes, escape the double quotes:
+Note that the URL in this example is enclosed in single quotes to prevent the
+shell from interpreting the double quotes. Alternatively, you may escape the
+double quotes with backslashes:
 
 ```sh
 curl http://localhost:26657/broadcast_tx_commit?tx=\"hello\"
 ```
 
-Using a special character:
+The double-quoted format works with for multibyte characters, as long as they
+are valid UTF8, for example:
 
 ```sh
 curl 'http://localhost:26657/broadcast_tx_commit?tx="€5"'
 ```
 
-sends a 4 byte transaction: "€5" (UTF8) \[e2 82 ac 35\].
+sends a 4-byte transaction: "€5" (UTF8) \[e2 82 ac 35\].
 
-To send as raw hex, omit quotes AND prefix the hex string with `0x`:
+Arbitrary (non-UTF8) transaction data may also be encoded as a string of
+hexadecimal digits (2 digits per byte). To do this, omit the quotation marks
+and prefix the hex string with `0x`:
 
 ```sh
-curl http://localhost:26657/broadcast_tx_commit?tx=0x01020304
+curl http://localhost:26657/broadcast_tx_commit?tx=0x68656C6C6F
 ```
 
-which sends a 4 byte transaction: \[01 02 03 04\].
+which sends the 5-byte transaction: \[68 65 6c 6c 6f\].
 
-With `POST` (using `json`), the raw hex must be `base64` encoded:
+Using `POST` (with parameters in JSON), the transaction data are sent as a JSON
+string in base64 encoding:
 
 ```sh
-curl --data-binary '{"jsonrpc":"2.0","id":"anything","method":"broadcast_tx_commit","params": {"tx": "AQIDBA=="}}' -H 'content-type:text/plain;' http://localhost:26657
+curl http://localhost:26657 -H 'Content-Type: application/json' --data-binary '{
+  "jsonrpc": "2.0",
+  "id": "anything",
+  "method": "broadcast_tx_commit",
+  "params": {
+    "tx": "aGVsbG8="
+  }
+}'
 ```
 
-which sends the same 4 byte transaction: \[01 02 03 04\].
+which sends the same 5-byte transaction: \[68 65 6c 6c 6f\].
 
-Note that raw hex cannot be used in `POST` transactions.
+Note that the hexadecimal encoding of transaction data is _not_ supported in
+JSON (`POST`) requests.
 
 ## Reset
 
diff --git a/light/rpc/client.go b/light/rpc/client.go
index 48cf7ce73..84761fb04 100644
--- a/light/rpc/client.go
+++ b/light/rpc/client.go
@@ -341,7 +341,7 @@ func (c *Client) Block(ctx context.Context, height *int64) (*ctypes.ResultBlock,
 }
 
 // BlockByHash calls rpcclient#BlockByHash and then verifies the result.
-func (c *Client) BlockByHash(ctx context.Context, hash []byte) (*ctypes.ResultBlock, error) {
+func (c *Client) BlockByHash(ctx context.Context, hash tmbytes.HexBytes) (*ctypes.ResultBlock, error) {
 	res, err := c.next.BlockByHash(ctx, hash)
 	if err != nil {
 		return nil, err
@@ -454,7 +454,7 @@ func (c *Client) Commit(ctx context.Context, height *int64) (*ctypes.ResultCommi
 
 // Tx calls rpcclient#Tx method and then verifies the proof if such was
 // requested.
-func (c *Client) Tx(ctx context.Context, hash []byte, prove bool) (*ctypes.ResultTx, error) {
+func (c *Client) Tx(ctx context.Context, hash tmbytes.HexBytes, prove bool) (*ctypes.ResultTx, error) {
 	res, err := c.next.Tx(ctx, hash, prove)
 	if err != nil || !prove {
 		return res, err
diff --git a/rpc/client/http/http.go b/rpc/client/http/http.go
index 54c56f99f..26a0ea5de 100644
--- a/rpc/client/http/http.go
+++ b/rpc/client/http/http.go
@@ -419,7 +419,7 @@ func (c *baseRPCClient) Block(ctx context.Context, height *int64) (*ctypes.Resul
 	return result, nil
 }
 
-func (c *baseRPCClient) BlockByHash(ctx context.Context, hash []byte) (*ctypes.ResultBlock, error) {
+func (c *baseRPCClient) BlockByHash(ctx context.Context, hash bytes.HexBytes) (*ctypes.ResultBlock, error) {
 	result := new(ctypes.ResultBlock)
 	params := map[string]interface{}{
 		"hash": hash,
@@ -460,7 +460,7 @@ func (c *baseRPCClient) Commit(ctx context.Context, height *int64) (*ctypes.Resu
 	return result, nil
 }
 
-func (c *baseRPCClient) Tx(ctx context.Context, hash []byte, prove bool) (*ctypes.ResultTx, error) {
+func (c *baseRPCClient) Tx(ctx context.Context, hash bytes.HexBytes, prove bool) (*ctypes.ResultTx, error) {
 	result := new(ctypes.ResultTx)
 	params := map[string]interface{}{
 		"hash":  hash,
diff --git a/rpc/client/interface.go b/rpc/client/interface.go
index 3547b42ae..8244e9295 100644
--- a/rpc/client/interface.go
+++ b/rpc/client/interface.go
@@ -67,11 +67,11 @@ type ABCIClient interface {
 // and prove anything about the chain.
 type SignClient interface {
 	Block(ctx context.Context, height *int64) (*ctypes.ResultBlock, error)
-	BlockByHash(ctx context.Context, hash []byte) (*ctypes.ResultBlock, error)
+	BlockByHash(ctx context.Context, hash bytes.HexBytes) (*ctypes.ResultBlock, error)
 	BlockResults(ctx context.Context, height *int64) (*ctypes.ResultBlockResults, error)
 	Commit(ctx context.Context, height *int64) (*ctypes.ResultCommit, error)
 	Validators(ctx context.Context, height *int64, page, perPage *int) (*ctypes.ResultValidators, error)
-	Tx(ctx context.Context, hash []byte, prove bool) (*ctypes.ResultTx, error)
+	Tx(ctx context.Context, hash bytes.HexBytes, prove bool) (*ctypes.ResultTx, error)
 
 	// TxSearch defines a method to search for a paginated set of transactions by
 	// DeliverTx event search criteria.
diff --git a/rpc/client/local/local.go b/rpc/client/local/local.go
index d752e6a93..39c4295ac 100644
--- a/rpc/client/local/local.go
+++ b/rpc/client/local/local.go
@@ -166,7 +166,7 @@ func (c *Local) Block(ctx context.Context, height *int64) (*ctypes.ResultBlock,
 	return c.env.Block(c.ctx, height)
 }
 
-func (c *Local) BlockByHash(ctx context.Context, hash []byte) (*ctypes.ResultBlock, error) {
+func (c *Local) BlockByHash(ctx context.Context, hash bytes.HexBytes) (*ctypes.ResultBlock, error) {
 	return c.env.BlockByHash(c.ctx, hash)
 }
 
@@ -182,7 +182,7 @@ func (c *Local) Validators(ctx context.Context, height *int64, page, perPage *in
 	return c.env.Validators(c.ctx, height, page, perPage)
 }
 
-func (c *Local) Tx(ctx context.Context, hash []byte, prove bool) (*ctypes.ResultTx, error) {
+func (c *Local) Tx(ctx context.Context, hash bytes.HexBytes, prove bool) (*ctypes.ResultTx, error) {
 	return c.env.Tx(c.ctx, hash, prove)
 }
 
diff --git a/rpc/client/mock/client.go b/rpc/client/mock/client.go
index 57e96fb09..8ff474dd5 100644
--- a/rpc/client/mock/client.go
+++ b/rpc/client/mock/client.go
@@ -166,7 +166,7 @@ func (c Client) Block(ctx context.Context, height *int64) (*ctypes.ResultBlock,
 	return c.env.Block(&rpctypes.Context{}, height)
 }
 
-func (c Client) BlockByHash(ctx context.Context, hash []byte) (*ctypes.ResultBlock, error) {
+func (c Client) BlockByHash(ctx context.Context, hash bytes.HexBytes) (*ctypes.ResultBlock, error) {
 	return c.env.BlockByHash(&rpctypes.Context{}, hash)
 }
 
diff --git a/rpc/client/mocks/client.go b/rpc/client/mocks/client.go
index ef374b9a8..8e4c7cbf5 100644
--- a/rpc/client/mocks/client.go
+++ b/rpc/client/mocks/client.go
@@ -115,11 +115,11 @@ func (_m *Client) Block(ctx context.Context, height *int64) (*coretypes.ResultBl
 }
 
 // BlockByHash provides a mock function with given fields: ctx, hash
-func (_m *Client) BlockByHash(ctx context.Context, hash []byte) (*coretypes.ResultBlock, error) {
+func (_m *Client) BlockByHash(ctx context.Context, hash bytes.HexBytes) (*coretypes.ResultBlock, error) {
 	ret := _m.Called(ctx, hash)
 
 	var r0 *coretypes.ResultBlock
-	if rf, ok := ret.Get(0).(func(context.Context, []byte) *coretypes.ResultBlock); ok {
+	if rf, ok := ret.Get(0).(func(context.Context, bytes.HexBytes) *coretypes.ResultBlock); ok {
 		r0 = rf(ctx, hash)
 	} else {
 		if ret.Get(0) != nil {
@@ -128,7 +128,7 @@ func (_m *Client) BlockByHash(ctx context.Context, hash []byte) (*coretypes.Resu
 	}
 
 	var r1 error
-	if rf, ok := ret.Get(1).(func(context.Context, []byte) error); ok {
+	if rf, ok := ret.Get(1).(func(context.Context, bytes.HexBytes) error); ok {
 		r1 = rf(ctx, hash)
 	} else {
 		r1 = ret.Error(1)
@@ -706,11 +706,11 @@ func (_m *Client) Subscribe(ctx context.Context, subscriber string, query string
 }
 
 // Tx provides a mock function with given fields: ctx, hash, prove
-func (_m *Client) Tx(ctx context.Context, hash []byte, prove bool) (*coretypes.ResultTx, error) {
+func (_m *Client) Tx(ctx context.Context, hash bytes.HexBytes, prove bool) (*coretypes.ResultTx, error) {
 	ret := _m.Called(ctx, hash, prove)
 
 	var r0 *coretypes.ResultTx
-	if rf, ok := ret.Get(0).(func(context.Context, []byte, bool) *coretypes.ResultTx); ok {
+	if rf, ok := ret.Get(0).(func(context.Context, bytes.HexBytes, bool) *coretypes.ResultTx); ok {
 		r0 = rf(ctx, hash, prove)
 	} else {
 		if ret.Get(0) != nil {
@@ -719,7 +719,7 @@ func (_m *Client) Tx(ctx context.Context, hash []byte, prove bool) (*coretypes.R
 	}
 
 	var r1 error
-	if rf, ok := ret.Get(1).(func(context.Context, []byte, bool) error); ok {
+	if rf, ok := ret.Get(1).(func(context.Context, bytes.HexBytes, bool) error); ok {
 		r1 = rf(ctx, hash, prove)
 	} else {
 		r1 = ret.Error(1)
diff --git a/rpc/core/blocks.go b/rpc/core/blocks.go
index 081276d0f..78b567583 100644
--- a/rpc/core/blocks.go
+++ b/rpc/core/blocks.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"sort"
 
+	"github.com/tendermint/tendermint/libs/bytes"
 	tmmath "github.com/tendermint/tendermint/libs/math"
 	tmquery "github.com/tendermint/tendermint/libs/pubsub/query"
 	ctypes "github.com/tendermint/tendermint/rpc/core/types"
@@ -107,7 +108,11 @@ func (env *Environment) Block(ctx *rpctypes.Context, heightPtr *int64) (*ctypes.
 
 // BlockByHash gets block by hash.
 // More: https://docs.tendermint.com/master/rpc/#/Info/block_by_hash
-func (env *Environment) BlockByHash(ctx *rpctypes.Context, hash []byte) (*ctypes.ResultBlock, error) {
+func (env *Environment) BlockByHash(ctx *rpctypes.Context, hash bytes.HexBytes) (*ctypes.ResultBlock, error) {
+	// N.B. The hash parameter is HexBytes so that the reflective parameter
+	// decoding logic in the HTTP service will correctly translate from JSON.
+	// See https://github.com/tendermint/tendermint/issues/6802 for context.
+
 	block := env.BlockStore.LoadBlockByHash(hash)
 	if block == nil {
 		return &ctypes.ResultBlock{BlockID: types.BlockID{}, Block: nil}, nil
diff --git a/rpc/core/tx.go b/rpc/core/tx.go
index 1b3da3075..eb6c73858 100644
--- a/rpc/core/tx.go
+++ b/rpc/core/tx.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"sort"
 
+	"github.com/tendermint/tendermint/libs/bytes"
 	tmmath "github.com/tendermint/tendermint/libs/math"
 	tmquery "github.com/tendermint/tendermint/libs/pubsub/query"
 	ctypes "github.com/tendermint/tendermint/rpc/core/types"
@@ -17,9 +18,13 @@ import (
 // transaction is in the mempool, invalidated, or was not sent in the first
 // place.
 // More: https://docs.tendermint.com/master/rpc/#/Info/tx
-func (env *Environment) Tx(ctx *rpctypes.Context, hash []byte, prove bool) (*ctypes.ResultTx, error) {
+func (env *Environment) Tx(ctx *rpctypes.Context, hash bytes.HexBytes, prove bool) (*ctypes.ResultTx, error) {
 	// if index is disabled, return error
 
+	// N.B. The hash parameter is HexBytes so that the reflective parameter
+	// decoding logic in the HTTP service will correctly translate from JSON.
+	// See https://github.com/tendermint/tendermint/issues/6802 for context.
+
 	if !indexer.KVSinkEnabled(env.EventSinks) {
 		return nil, errors.New("transaction querying is disabled due to no kvEventSink")
 	}