diff --git a/pkg/rpc/request/param.go b/pkg/rpc/request/param.go
index 4918645bc..f67d2f81c 100644
--- a/pkg/rpc/request/param.go
+++ b/pkg/rpc/request/param.go
@@ -2,6 +2,7 @@ package request
 
 import (
 	"bytes"
+	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
@@ -185,6 +186,17 @@ func (p *Param) GetBytesHex() ([]byte, error) {
 	return hex.DecodeString(s)
 }
 
+// GetBytesBase64 returns []byte value of the parameter if
+// it is a base64-encoded string.
+func (p *Param) GetBytesBase64() ([]byte, error) {
+	s, err := p.GetString()
+	if err != nil {
+		return nil, err
+	}
+
+	return base64.StdEncoding.DecodeString(s)
+}
+
 // GetCosigner returns transaction.Cosigner value of the parameter.
 func (p Param) GetCosigner() (transaction.Cosigner, error) {
 	c, ok := p.Value.(transaction.Cosigner)
diff --git a/pkg/rpc/request/param_test.go b/pkg/rpc/request/param_test.go
index 70a40b41f..674262b08 100644
--- a/pkg/rpc/request/param_test.go
+++ b/pkg/rpc/request/param_test.go
@@ -1,6 +1,7 @@
 package request
 
 import (
+	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
 	"testing"
@@ -242,6 +243,24 @@ func TestParamGetBytesHex(t *testing.T) {
 	require.NotNil(t, err)
 }
 
+func TestParamGetBytesBase64(t *testing.T) {
+	in := "Aj4A8DoW6HB84EXrQu6A05JFFUHuUQ3BjhyL77rFTXQm"
+	inb, err := base64.StdEncoding.DecodeString(in)
+	require.NoError(t, err)
+	p := Param{StringT, in}
+	bh, err := p.GetBytesBase64()
+	assert.Equal(t, inb, bh)
+	require.Nil(t, err)
+
+	p = Param{StringT, 42}
+	_, err = p.GetBytesBase64()
+	require.NotNil(t, err)
+
+	p = Param{StringT, "@j4A8DoW6HB84EXrQu6A05JFFUHuUQ3BjhyL77rFTXQm"}
+	_, err = p.GetBytesBase64()
+	require.NotNil(t, err)
+}
+
 func TestParamGetCosigner(t *testing.T) {
 	c := transaction.Cosigner{
 		Account: util.Uint160{1, 2, 3, 4},
diff --git a/pkg/rpc/request/txBuilder.go b/pkg/rpc/request/txBuilder.go
index f8db67de2..c3b76d91e 100644
--- a/pkg/rpc/request/txBuilder.go
+++ b/pkg/rpc/request/txBuilder.go
@@ -37,7 +37,13 @@ func expandArrayIntoScript(script *io.BinWriter, slice []Param) error {
 			return err
 		}
 		switch fp.Type {
-		case smartcontract.ByteArrayType, smartcontract.SignatureType:
+		case smartcontract.ByteArrayType:
+			str, err := fp.Value.GetBytesBase64()
+			if err != nil {
+				return err
+			}
+			emit.Bytes(script, str)
+		case smartcontract.SignatureType:
 			str, err := fp.Value.GetBytesHex()
 			if err != nil {
 				return err
diff --git a/pkg/rpc/request/tx_builder_test.go b/pkg/rpc/request/tx_builder_test.go
index a132c629f..dd849da0f 100644
--- a/pkg/rpc/request/tx_builder_test.go
+++ b/pkg/rpc/request/tx_builder_test.go
@@ -30,8 +30,8 @@ func TestInvocationScriptCreationGood(t *testing.T) {
 		ps:     Params{{Type: StringT, Value: "a"}, {Type: ArrayT, Value: []Param{}}},
 		script: "10c00c01610c146f459162ceeb248b071ec157d9e4f6fd26fdbe5041627d5b52",
 	}, {
-		ps:     Params{{Type: StringT, Value: "a"}, {Type: ArrayT, Value: []Param{{Type: FuncParamT, Value: FuncParam{Type: smartcontract.ByteArrayType, Value: Param{Type: StringT, Value: "50befd26fdf6e4d957c11e078b24ebce6291456f"}}}}}},
-		script: "0c1450befd26fdf6e4d957c11e078b24ebce6291456f11c00c01610c146f459162ceeb248b071ec157d9e4f6fd26fdbe5041627d5b52",
+		ps:     Params{{Type: StringT, Value: "a"}, {Type: ArrayT, Value: []Param{{Type: FuncParamT, Value: FuncParam{Type: smartcontract.ByteArrayType, Value: Param{Type: StringT, Value: "AwEtR+diEK7HO+Oas9GG4KQP6Nhr+j1Pq/2le6E7iPlq"}}}}}},
+		script: "0c2103012d47e76210aec73be39ab3d186e0a40fe8d86bfa3d4fabfda57ba13b88f96a11c00c01610c146f459162ceeb248b071ec157d9e4f6fd26fdbe5041627d5b52",
 	}, {
 		ps:     Params{{Type: StringT, Value: "a"}, {Type: ArrayT, Value: []Param{{Type: FuncParamT, Value: FuncParam{Type: smartcontract.SignatureType, Value: Param{Type: StringT, Value: "4edf5005771de04619235d5a4c7a9a11bb78e008541f1da7725f654c33380a3c87e2959a025da706d7255cb3a3fa07ebe9c6559d0d9e6213c68049168eb1056f"}}}}}},
 		script: "0c404edf5005771de04619235d5a4c7a9a11bb78e008541f1da7725f654c33380a3c87e2959a025da706d7255cb3a3fa07ebe9c6559d0d9e6213c68049168eb1056f11c00c01610c146f459162ceeb248b071ec157d9e4f6fd26fdbe5041627d5b52",