diff --git a/pkg/rpc/rpc.go b/pkg/rpc/rpc.go
index a4d7f32e2..0c336c8b1 100644
--- a/pkg/rpc/rpc.go
+++ b/pkg/rpc/rpc.go
@@ -57,6 +57,19 @@ func (c *Client) InvokeFunction(script, operation string, params []smartcontract
 	return resp, nil
 }
 
+// InvokeFunction return the results after calling a the smart contract scripthash
+// with the given parameters.
+func (c *Client) Invoke(script string, params []smartcontract.Parameter) (*InvokeScriptResponse, error) {
+	var (
+		p    = newParams(script, params)
+		resp = &InvokeScriptResponse{}
+	)
+	if err := c.performRequest("invoke", p, resp); err != nil {
+		return nil, err
+	}
+	return resp, nil
+}
+
 // GetRawTransaction queries a transaction by hash.
 func (c *Client) GetRawTransaction(hash string, verbose bool) (*response, error) {
 	var (
diff --git a/pkg/smartcontract/param_context.go b/pkg/smartcontract/param_context.go
index 4344d9644..c8c2504b2 100644
--- a/pkg/smartcontract/param_context.go
+++ b/pkg/smartcontract/param_context.go
@@ -26,6 +26,35 @@ type Parameter struct {
 	Value interface{} `json:"value"`
 }
 
+func (pt ParamType) String() string {
+    switch pt {
+    case SignatureType:
+	return "Signature"
+    case BoolType:
+	return "Boolean"
+    case IntegerType:
+	return "Integer"
+    case Hash160Type:
+	return "Hash160"
+    case Hash256Type:
+	return "Hash256"
+    case ByteArrayType:
+	return "ByteArray"
+    case PublicKeyType:
+	return "PublicKey"
+    case StringType:
+	return "String"
+    case ArrayType:
+	return "Array"
+    default:
+        return ""
+    }
+}
+
+func (pt ParamType) MarshalJSON() ([]byte, error) {
+    return []byte(`"` + pt.String() + `"`), nil
+}
+
 // NewParameter returns a Parameter with proper initialized Value
 // of the given ParamType.
 func NewParameter(t ParamType) Parameter {