diff --git a/pkg/smartcontract/callflag/call_flags.go b/pkg/smartcontract/callflag/call_flags.go
index 07bbb15b4..c31b819b4 100644
--- a/pkg/smartcontract/callflag/call_flags.go
+++ b/pkg/smartcontract/callflag/call_flags.go
@@ -1,5 +1,11 @@
 package callflag
 
+import (
+	"encoding/json"
+	"errors"
+	"strings"
+)
+
 // CallFlag represents call flag.
 type CallFlag byte
 
@@ -16,7 +22,98 @@ const (
 	NoneFlag CallFlag = 0
 )
 
+var flagString = map[CallFlag]string{
+	ReadStates:  "ReadStates",
+	WriteStates: "WriteStates",
+	AllowCall:   "AllowCall",
+	AllowNotify: "AllowNotify",
+	States:      "States",
+	ReadOnly:    "ReadOnly",
+	All:         "All",
+	NoneFlag:    "None",
+}
+
+// basicFlags are all flags except All and None. It's used to stringify CallFlag
+// where its bits are matched against these values from values with sets of bits
+// to simple flags which is important to produce proper string representation
+// matching C# Enum handling.
+var basicFlags = []CallFlag{ReadOnly, States, ReadStates, WriteStates, AllowCall, AllowNotify}
+
+// FromString parses input string and returns corresponding CallFlag.
+func FromString(s string) (CallFlag, error) {
+	flags := strings.Split(s, ",")
+	if len(flags) == 0 {
+		return NoneFlag, errors.New("empty flags")
+	}
+	if len(flags) == 1 {
+		for f, str := range flagString {
+			if s == str {
+				return f, nil
+			}
+		}
+		return NoneFlag, errors.New("unknown flag")
+	}
+
+	var res CallFlag
+
+	for _, flag := range flags {
+		var knownFlag bool
+
+		flag = strings.TrimSpace(flag)
+		for _, f := range basicFlags {
+			if flag == flagString[f] {
+				res |= f
+				knownFlag = true
+				break
+			}
+		}
+		if !knownFlag {
+			return NoneFlag, errors.New("unknown/inappropriate flag")
+		}
+	}
+	return res, nil
+}
+
 // Has returns true iff all bits set in cf are also set in f.
 func (f CallFlag) Has(cf CallFlag) bool {
 	return f&cf == cf
 }
+
+// String implements Stringer interface.
+func (f CallFlag) String() string {
+	if flagString[f] != "" {
+		return flagString[f]
+	}
+
+	var res string
+
+	for _, flag := range basicFlags {
+		if f.Has(flag) {
+			if len(res) != 0 {
+				res += ", "
+			}
+			res += flagString[flag]
+			f &= ^flag // Some "States" shouldn't be combined with "ReadStates".
+		}
+	}
+	return res
+}
+
+// MarshalJSON implements json.Marshaler interface.
+func (f CallFlag) MarshalJSON() ([]byte, error) {
+	return []byte(`"` + f.String() + `"`), nil
+}
+
+// UnmarshalJSON implements json.Unmarshaler interface.
+func (f *CallFlag) UnmarshalJSON(data []byte) error {
+	var js string
+	if err := json.Unmarshal(data, &js); err != nil {
+		return err
+	}
+	flag, err := FromString(js)
+	if err != nil {
+		return err
+	}
+	*f = flag
+	return nil
+}
diff --git a/pkg/smartcontract/callflag/call_flags_test.go b/pkg/smartcontract/callflag/call_flags_test.go
index 7dd9048b8..b75145150 100644
--- a/pkg/smartcontract/callflag/call_flags_test.go
+++ b/pkg/smartcontract/callflag/call_flags_test.go
@@ -3,6 +3,7 @@ package callflag
 import (
 	"testing"
 
+	"github.com/nspcc-dev/neo-go/internal/testserdes"
 	"github.com/stretchr/testify/require"
 )
 
@@ -12,3 +13,65 @@ func TestCallFlag_Has(t *testing.T) {
 	require.False(t, (AllowCall).Has(AllowCall|AllowNotify))
 	require.True(t, All.Has(ReadOnly))
 }
+
+func TestCallFlagString(t *testing.T) {
+	var cases = map[CallFlag]string{
+		NoneFlag:               "None",
+		All:                    "All",
+		ReadStates:             "ReadStates",
+		States:                 "States",
+		ReadOnly:               "ReadOnly",
+		States | AllowCall:     "ReadOnly, WriteStates",
+		ReadOnly | AllowNotify: "ReadOnly, AllowNotify",
+		States | AllowNotify:   "States, AllowNotify",
+	}
+	for f, s := range cases {
+		require.Equal(t, s, f.String())
+	}
+}
+
+func TestFromString(t *testing.T) {
+	var cases = map[string]struct {
+		flag CallFlag
+		err  bool
+	}{
+		"None":                   {NoneFlag, false},
+		"All":                    {All, false},
+		"ReadStates":             {ReadStates, false},
+		"States":                 {States, false},
+		"ReadOnly":               {ReadOnly, false},
+		"ReadOnly, WriteStates":  {States | AllowCall, false},
+		"States, AllowCall":      {States | AllowCall, false},
+		"AllowCall, States":      {States | AllowCall, false},
+		"States, ReadOnly":       {States | AllowCall, false},
+		" AllowCall,AllowNotify": {AllowNotify | AllowCall, false},
+		"BlahBlah":               {NoneFlag, true},
+		"States, All":            {NoneFlag, true},
+		"ReadStates,,AllowCall":  {NoneFlag, true},
+		"ReadStates;AllowCall":   {NoneFlag, true},
+		"readstates":             {NoneFlag, true},
+		"  All":                  {NoneFlag, true},
+		"None, All":              {NoneFlag, true},
+	}
+	for s, res := range cases {
+		f, err := FromString(s)
+		require.True(t, res.err == (err != nil), "Input: '"+s+"'")
+		require.Equal(t, res.flag, f)
+	}
+}
+
+func TestMarshalUnmarshalJSON(t *testing.T) {
+	var f = States
+	testserdes.MarshalUnmarshalJSON(t, &f, new(CallFlag))
+	f = States | AllowNotify
+	testserdes.MarshalUnmarshalJSON(t, &f, new(CallFlag))
+
+	forig := f
+	err := f.UnmarshalJSON([]byte("42"))
+	require.Error(t, err)
+	require.Equal(t, forig, f)
+
+	err = f.UnmarshalJSON([]byte(`"State"`))
+	require.Error(t, err)
+	require.Equal(t, forig, f)
+}
diff --git a/pkg/smartcontract/nef/nef_test.go b/pkg/smartcontract/nef/nef_test.go
index 8c52bae2c..03d3af86c 100644
--- a/pkg/smartcontract/nef/nef_test.go
+++ b/pkg/smartcontract/nef/nef_test.go
@@ -147,7 +147,7 @@ func TestMarshalUnmarshalJSON(t *testing.T) {
 	"method": "someMethod",
 	"paramcount": 3,
 	"hasreturnvalue": true,
-	"callflags": `+strconv.FormatInt(int64(expected.Tokens[0].CallFlag), 10)+`
+	"callflags": "`+expected.Tokens[0].CallFlag.String()+`"
 			}
 		],
 		"script": "`+base64.StdEncoding.EncodeToString(expected.Script)+`",