diff --git a/pkg/core/transaction/attribute_test.go b/pkg/core/transaction/attribute_test.go
index 4d43df95f..b38c88181 100644
--- a/pkg/core/transaction/attribute_test.go
+++ b/pkg/core/transaction/attribute_test.go
@@ -29,6 +29,18 @@ func TestAttribute_EncodeBinary(t *testing.T) {
 			},
 		}
 		testserdes.EncodeDecodeBinary(t, attr, new(Attribute))
+		for _, code := range []OracleResponseCode{ProtocolNotSupported, ConsensusUnreachable,
+			NotFound, Timeout, Forbidden, ResponseTooLarge, InsufficientFunds, Error} {
+			attr = &Attribute{
+				Type: OracleResponseT,
+				Value: &OracleResponse{
+					ID:     42,
+					Code:   code,
+					Result: []byte{},
+				},
+			}
+			testserdes.EncodeDecodeBinary(t, attr, new(Attribute))
+		}
 	})
 	t.Run("NotValidBefore", func(t *testing.T) {
 		t.Run("positive", func(t *testing.T) {
@@ -144,7 +156,7 @@ func TestAttribute_MarshalJSON(t *testing.T) {
 		require.JSONEq(t, `{
 			"type":"OracleResponse",
 			"id": 123,
-			"code": 0,
+			"code": "Success",
 			"result": "`+base64.StdEncoding.EncodeToString(res)+`"}`, string(data))
 
 		actual := new(Attribute)
diff --git a/pkg/core/transaction/oracle.go b/pkg/core/transaction/oracle.go
index 477567810..3c89d644c 100644
--- a/pkg/core/transaction/oracle.go
+++ b/pkg/core/transaction/oracle.go
@@ -1,12 +1,16 @@
 package transaction
 
 import (
+	"encoding/json"
 	"errors"
 	"math"
+	"strings"
 
 	"github.com/nspcc-dev/neo-go/pkg/io"
 )
 
+//go:generate stringer -type=OracleResponseCode
+
 // OracleResponseCode represents result code of oracle response.
 type OracleResponseCode byte
 
@@ -46,6 +50,43 @@ func (c OracleResponseCode) IsValid() bool {
 		c == InsufficientFunds || c == Error
 }
 
+// MarshalJSON implements json.Marshaler interface.
+func (c OracleResponseCode) MarshalJSON() ([]byte, error) {
+	return []byte(`"` + c.String() + `"`), nil
+}
+
+// UnmarshalJSON implements json.Unmarshaler interface.
+func (c *OracleResponseCode) UnmarshalJSON(data []byte) error {
+	var js string
+	if err := json.Unmarshal(data, &js); err != nil {
+		return err
+	}
+	js = strings.ToLower(js)
+	switch js {
+	case "success":
+		*c = Success
+	case "protocolnotsupported":
+		*c = ProtocolNotSupported
+	case "consensusunreachable":
+		*c = ConsensusUnreachable
+	case "notfound":
+		*c = NotFound
+	case "timeout":
+		*c = Timeout
+	case "forbidden":
+		*c = Forbidden
+	case "responsetoolarge":
+		*c = ResponseTooLarge
+	case "insufficientfunds":
+		*c = InsufficientFunds
+	case "error":
+		*c = Error
+	default:
+		return errors.New("invalid oracle response code")
+	}
+	return nil
+}
+
 // DecodeBinary implements io.Serializable interface.
 func (r *OracleResponse) DecodeBinary(br *io.BinReader) {
 	r.ID = br.ReadU64LE()
diff --git a/pkg/core/transaction/oracleresponsecode_string.go b/pkg/core/transaction/oracleresponsecode_string.go
new file mode 100644
index 000000000..53a57e45c
--- /dev/null
+++ b/pkg/core/transaction/oracleresponsecode_string.go
@@ -0,0 +1,57 @@
+// Code generated by "stringer -type=OracleResponseCode"; DO NOT EDIT.
+
+package transaction
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[Success-0]
+	_ = x[ProtocolNotSupported-16]
+	_ = x[ConsensusUnreachable-18]
+	_ = x[NotFound-20]
+	_ = x[Timeout-22]
+	_ = x[Forbidden-24]
+	_ = x[ResponseTooLarge-26]
+	_ = x[InsufficientFunds-28]
+	_ = x[Error-255]
+}
+
+const (
+	_OracleResponseCode_name_0 = "Success"
+	_OracleResponseCode_name_1 = "ProtocolNotSupported"
+	_OracleResponseCode_name_2 = "ConsensusUnreachable"
+	_OracleResponseCode_name_3 = "NotFound"
+	_OracleResponseCode_name_4 = "Timeout"
+	_OracleResponseCode_name_5 = "Forbidden"
+	_OracleResponseCode_name_6 = "ResponseTooLarge"
+	_OracleResponseCode_name_7 = "InsufficientFunds"
+	_OracleResponseCode_name_8 = "Error"
+)
+
+func (i OracleResponseCode) String() string {
+	switch {
+	case i == 0:
+		return _OracleResponseCode_name_0
+	case i == 16:
+		return _OracleResponseCode_name_1
+	case i == 18:
+		return _OracleResponseCode_name_2
+	case i == 20:
+		return _OracleResponseCode_name_3
+	case i == 22:
+		return _OracleResponseCode_name_4
+	case i == 24:
+		return _OracleResponseCode_name_5
+	case i == 26:
+		return _OracleResponseCode_name_6
+	case i == 28:
+		return _OracleResponseCode_name_7
+	case i == 255:
+		return _OracleResponseCode_name_8
+	default:
+		return "OracleResponseCode(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+}