diff --git a/pkg/core/blockchain.go b/pkg/core/blockchain.go
index e5a7a5519..c47a97283 100644
--- a/pkg/core/blockchain.go
+++ b/pkg/core/blockchain.go
@@ -29,7 +29,7 @@ import (
 // Tuning parameters.
 const (
 	headerBatchCount = 2000
-	version          = "0.0.8"
+	version          = "0.0.9"
 
 	// This one comes from C# code and it's different from the constant used
 	// when creating an asset with Neo.Asset.Create interop call. It looks
@@ -708,7 +708,7 @@ func (bc *Blockchain) storeBlock(block *block.Block) error {
 				Trigger:     trigger.Application,
 				VMState:     v.State(),
 				GasConsumed: v.GasConsumed(),
-				Stack:       v.Stack("estack"),
+				Stack:       v.Estack().ToContractParameters(),
 				Events:      systemInterop.notifications,
 			}
 			err = cache.PutAppExecResult(aer)
diff --git a/pkg/core/dao_test.go b/pkg/core/dao_test.go
index 94125ecd7..b49296658 100644
--- a/pkg/core/dao_test.go
+++ b/pkg/core/dao_test.go
@@ -171,7 +171,11 @@ func TestGetValidators(t *testing.T) {
 func TestPutGetAppExecResult(t *testing.T) {
 	dao := newDao(storage.NewMemoryStore())
 	hash := random.Uint256()
-	appExecResult := &state.AppExecResult{TxHash: hash, Events: []state.NotificationEvent{}}
+	appExecResult := &state.AppExecResult{
+		TxHash: hash,
+		Events: []state.NotificationEvent{},
+		Stack:  []smartcontract.Parameter{},
+	}
 	err := dao.PutAppExecResult(appExecResult)
 	require.NoError(t, err)
 	gotAppExecResult, err := dao.GetAppExecResult(hash)
diff --git a/pkg/core/state/notification_event.go b/pkg/core/state/notification_event.go
index 24e6659e8..2599f781e 100644
--- a/pkg/core/state/notification_event.go
+++ b/pkg/core/state/notification_event.go
@@ -2,6 +2,7 @@ package state
 
 import (
 	"github.com/nspcc-dev/neo-go/pkg/io"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neo-go/pkg/vm"
@@ -21,7 +22,7 @@ type AppExecResult struct {
 	Trigger     trigger.Type
 	VMState     string
 	GasConsumed util.Fixed8
-	Stack       string // JSON
+	Stack       []smartcontract.Parameter
 	Events      []NotificationEvent
 }
 
@@ -43,7 +44,7 @@ func (aer *AppExecResult) EncodeBinary(w *io.BinWriter) {
 	w.WriteB(byte(aer.Trigger))
 	w.WriteString(aer.VMState)
 	aer.GasConsumed.EncodeBinary(w)
-	w.WriteString(aer.Stack)
+	w.WriteArray(aer.Stack)
 	w.WriteArray(aer.Events)
 }
 
@@ -53,6 +54,6 @@ func (aer *AppExecResult) DecodeBinary(r *io.BinReader) {
 	aer.Trigger = trigger.Type(r.ReadB())
 	aer.VMState = r.ReadString()
 	aer.GasConsumed.DecodeBinary(r)
-	aer.Stack = r.ReadString()
+	r.ReadArray(&aer.Stack)
 	r.ReadArray(&aer.Events)
 }
diff --git a/pkg/core/state/notification_event_test.go b/pkg/core/state/notification_event_test.go
index 0f28e2957..3deb48845 100644
--- a/pkg/core/state/notification_event_test.go
+++ b/pkg/core/state/notification_event_test.go
@@ -5,6 +5,7 @@ import (
 
 	"github.com/nspcc-dev/neo-go/pkg/internal/random"
 	"github.com/nspcc-dev/neo-go/pkg/io"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -30,7 +31,7 @@ func TestEncodeDecodeAppExecResult(t *testing.T) {
 		Trigger:     1,
 		VMState:     "Hault",
 		GasConsumed: 10,
-		Stack:       "",
+		Stack:       []smartcontract.Parameter{},
 		Events:      []NotificationEvent{},
 	}
 	buf := io.NewBufBinWriter()
diff --git a/pkg/rpc/response/result/application_log.go b/pkg/rpc/response/result/application_log.go
index 27e2026c0..da436f2f4 100644
--- a/pkg/rpc/response/result/application_log.go
+++ b/pkg/rpc/response/result/application_log.go
@@ -1,8 +1,6 @@
 package result
 
 import (
-	"encoding/json"
-
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/nspcc-dev/neo-go/pkg/util"
@@ -18,12 +16,12 @@ type ApplicationLog struct {
 
 // Execution response wrapper
 type Execution struct {
-	Trigger     string              `json:"trigger"`
-	ScriptHash  util.Uint160        `json:"contract"`
-	VMState     string              `json:"vmstate"`
-	GasConsumed util.Fixed8         `json:"gas_consumed"`
-	Stack       json.RawMessage     `json:"stack"`
-	Events      []NotificationEvent `json:"notifications"`
+	Trigger     string                    `json:"trigger"`
+	ScriptHash  util.Uint160              `json:"contract"`
+	VMState     string                    `json:"vmstate"`
+	GasConsumed util.Fixed8               `json:"gas_consumed"`
+	Stack       []smartcontract.Parameter `json:"stack"`
+	Events      []NotificationEvent       `json:"notifications"`
 }
 
 //NotificationEvent response wrapper
@@ -46,18 +44,12 @@ func NewApplicationLog(appExecRes *state.AppExecResult, scriptHash util.Uint160)
 
 	triggerString := appExecRes.Trigger.String()
 
-	var rawStack json.RawMessage
-	if len(appExecRes.Stack) != 0 {
-		rawStack = json.RawMessage(appExecRes.Stack)
-	} else {
-		rawStack = json.RawMessage("[]")
-	}
 	executions := []Execution{{
 		Trigger:     triggerString,
 		ScriptHash:  scriptHash,
 		VMState:     appExecRes.VMState,
 		GasConsumed: appExecRes.GasConsumed,
-		Stack:       rawStack,
+		Stack:       appExecRes.Stack,
 		Events:      events,
 	}}
 
diff --git a/pkg/smartcontract/parameter.go b/pkg/smartcontract/parameter.go
index 0a5c8b9ff..a5d49669f 100644
--- a/pkg/smartcontract/parameter.go
+++ b/pkg/smartcontract/parameter.go
@@ -4,11 +4,14 @@ import (
 	"encoding/binary"
 	"encoding/hex"
 	"encoding/json"
+	"fmt"
+	"math"
 	"math/bits"
 	"strconv"
 	"strings"
 	"unicode/utf8"
 
+	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/pkg/errors"
 )
@@ -210,6 +213,87 @@ func (p *Parameter) UnmarshalJSON(data []byte) (err error) {
 	return
 }
 
+// EncodeBinary implements io.Serializable interface.
+func (p *Parameter) EncodeBinary(w *io.BinWriter) {
+	w.WriteB(byte(p.Type))
+	switch p.Type {
+	case BoolType:
+		w.WriteBool(p.Value.(bool))
+	case ByteArrayType, PublicKeyType, SignatureType:
+		if p.Value == nil {
+			w.WriteVarUint(math.MaxUint64)
+		} else {
+			w.WriteVarBytes(p.Value.([]byte))
+		}
+	case StringType:
+		w.WriteString(p.Value.(string))
+	case IntegerType:
+		w.WriteU64LE(uint64(p.Value.(int64)))
+	case ArrayType:
+		w.WriteArray(p.Value.([]Parameter))
+	case MapType:
+		m := p.Value.(map[Parameter]Parameter)
+		w.WriteVarUint(uint64(len(m)))
+		for k := range m {
+			v := m[k]
+			k.EncodeBinary(w)
+			v.EncodeBinary(w)
+		}
+	case Hash160Type:
+		w.WriteBytes(p.Value.(util.Uint160).BytesBE())
+	case Hash256Type:
+		w.WriteBytes(p.Value.(util.Uint256).BytesBE())
+	case InteropInterfaceType:
+	default:
+		w.Err = fmt.Errorf("unknown type: %x", p.Type)
+	}
+}
+
+// DecodeBinary implements io.Serializable interface.
+func (p *Parameter) DecodeBinary(r *io.BinReader) {
+	p.Type = ParamType(r.ReadB())
+	switch p.Type {
+	case BoolType:
+		p.Value = r.ReadBool()
+	case ByteArrayType, PublicKeyType, SignatureType:
+		ln := r.ReadVarUint()
+		if ln != math.MaxUint64 {
+			b := make([]byte, ln)
+			r.ReadBytes(b)
+			p.Value = b
+		}
+	case StringType:
+		p.Value = r.ReadString()
+	case IntegerType:
+		p.Value = int64(r.ReadU64LE())
+	case ArrayType:
+		ps := []Parameter{}
+		r.ReadArray(&ps)
+		p.Value = ps
+	case MapType:
+		ln := r.ReadVarUint()
+		m := make(map[Parameter]Parameter, ln)
+		for i := uint64(0); i < ln; i++ {
+			var k, v Parameter
+			k.DecodeBinary(r)
+			v.DecodeBinary(r)
+			m[k] = v
+		}
+		p.Value = m
+	case Hash160Type:
+		var u util.Uint160
+		r.ReadBytes(u[:])
+		p.Value = u
+	case Hash256Type:
+		var u util.Uint256
+		r.ReadBytes(u[:])
+		p.Value = u
+	case InteropInterfaceType:
+	default:
+		r.Err = fmt.Errorf("unknown type: %x", p.Type)
+	}
+}
+
 // Params is an array of Parameter (TODO: drop it?).
 type Params []Parameter
 
diff --git a/pkg/smartcontract/parameter_test.go b/pkg/smartcontract/parameter_test.go
index 55c8c2fd7..a1715ee13 100644
--- a/pkg/smartcontract/parameter_test.go
+++ b/pkg/smartcontract/parameter_test.go
@@ -6,8 +6,10 @@ import (
 	"reflect"
 	"testing"
 
+	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 var marshalJSONTestCases = []struct {
@@ -71,7 +73,7 @@ var marshalJSONTestCases = []struct {
 		input: Parameter{
 			Type: MapType,
 			Value: map[Parameter]Parameter{
-				{Type: StringType, Value: "key1"}: {Type: IntegerType, Value: 1},
+				{Type: StringType, Value: "key1"}: {Type: IntegerType, Value: int64(1)},
 				{Type: StringType, Value: "key2"}: {Type: StringType, Value: "two"},
 			},
 		},
@@ -441,3 +443,28 @@ func TestNewParameterFromString(t *testing.T) {
 		}
 	}
 }
+
+func TestEncodeDecodeBinary(t *testing.T) {
+	for _, tc := range marshalJSONTestCases {
+		w := io.NewBufBinWriter()
+		tc.input.EncodeBinary(w.BinWriter)
+		require.NoError(t, w.Err)
+
+		r := io.NewBinReaderFromBuf(w.Bytes())
+		var p Parameter
+		p.DecodeBinary(r)
+		require.NoError(t, r.Err)
+		require.Equal(t, tc.input, p)
+	}
+
+	t.Run("unknown", func(t *testing.T) {
+		p := Parameter{Type: UnknownType}
+		w := io.NewBufBinWriter()
+		p.EncodeBinary(w.BinWriter)
+		require.Error(t, w.Err)
+
+		r := io.NewBinReaderFromBuf([]byte{0xAA})
+		p.DecodeBinary(r)
+		require.Error(t, r.Err)
+	})
+}