diff --git a/pkg/core/blockchain.go b/pkg/core/blockchain.go
index 68d849882..cd85cb01d 100644
--- a/pkg/core/blockchain.go
+++ b/pkg/core/blockchain.go
@@ -591,7 +591,7 @@ func (bc *Blockchain) storeBlock(block *block.Block) error {
 			Trigger:     trigger.System,
 			VMState:     v.State(),
 			GasConsumed: v.GasConsumed(),
-			Stack:       v.Estack().ToContractParameters(),
+			Stack:       v.Estack().ToArray(),
 			Events:      systemInterop.Notifications,
 		}
 		appExecResults = append(appExecResults, aer)
@@ -632,7 +632,7 @@ func (bc *Blockchain) storeBlock(block *block.Block) error {
 			Trigger:     trigger.Application,
 			VMState:     v.State(),
 			GasConsumed: v.GasConsumed(),
-			Stack:       v.Estack().ToContractParameters(),
+			Stack:       v.Estack().ToArray(),
 			Events:      systemInterop.Notifications,
 		}
 		appExecResults = append(appExecResults, aer)
diff --git a/pkg/core/dao/dao_test.go b/pkg/core/dao/dao_test.go
index a94649467..a9760b3dc 100644
--- a/pkg/core/dao/dao_test.go
+++ b/pkg/core/dao/dao_test.go
@@ -11,8 +11,8 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"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/nspcc-dev/neo-go/pkg/vm/opcode"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
 	"github.com/stretchr/testify/require"
 )
 
@@ -103,7 +103,7 @@ func TestPutGetAppExecResult(t *testing.T) {
 	appExecResult := &state.AppExecResult{
 		TxHash: hash,
 		Events: []state.NotificationEvent{},
-		Stack:  []smartcontract.Parameter{},
+		Stack:  []stackitem.Item{},
 	}
 	err := dao.PutAppExecResult(appExecResult)
 	require.NoError(t, err)
diff --git a/pkg/core/native_contract_test.go b/pkg/core/native_contract_test.go
index b1df21ea1..df6bad3ed 100644
--- a/pkg/core/native_contract_test.go
+++ b/pkg/core/native_contract_test.go
@@ -131,8 +131,7 @@ func TestNativeContract_Invoke(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, vm.HaltState, res.VMState)
 	require.Equal(t, 1, len(res.Stack))
-	require.Equal(t, smartcontract.IntegerType, res.Stack[0].Type)
-	require.EqualValues(t, 42, res.Stack[0].Value)
+	require.Equal(t, big.NewInt(42), res.Stack[0].Value())
 
 	res, err = chain.GetAppExecResult(tx2.Hash())
 	require.NoError(t, err)
diff --git a/pkg/core/native_policy_test.go b/pkg/core/native_policy_test.go
index b0fd12964..88b246335 100644
--- a/pkg/core/native_policy_test.go
+++ b/pkg/core/native_policy_test.go
@@ -10,10 +10,10 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/encoding/bigint"
 	"github.com/nspcc-dev/neo-go/pkg/io"
-	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neo-go/pkg/vm"
 	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
 	"github.com/stretchr/testify/require"
 )
 
@@ -29,20 +29,14 @@ func TestMaxTransactionsPerBlock(t *testing.T) {
 	t.Run("get, contract method", func(t *testing.T) {
 		res, err := invokeNativePolicyMethod(chain, "getMaxTransactionsPerBlock")
 		require.NoError(t, err)
-		checkResult(t, res, smartcontract.Parameter{
-			Type:  smartcontract.IntegerType,
-			Value: 512,
-		})
+		checkResult(t, res, stackitem.NewBigInteger(big.NewInt(512)))
 		require.NoError(t, chain.persist())
 	})
 
 	t.Run("set", func(t *testing.T) {
 		res, err := invokeNativePolicyMethod(chain, "setMaxTransactionsPerBlock", bigint.ToBytes(big.NewInt(1024)))
 		require.NoError(t, err)
-		checkResult(t, res, smartcontract.Parameter{
-			Type:  smartcontract.BoolType,
-			Value: true,
-		})
+		checkResult(t, res, stackitem.NewBool(true))
 		require.NoError(t, chain.persist())
 		n := chain.contracts.Policy.GetMaxTransactionsPerBlockInternal(chain.dao)
 		require.Equal(t, 1024, int(n))
@@ -56,27 +50,18 @@ func TestMaxBlockSize(t *testing.T) {
 	t.Run("get", func(t *testing.T) {
 		res, err := invokeNativePolicyMethod(chain, "getMaxBlockSize")
 		require.NoError(t, err)
-		checkResult(t, res, smartcontract.Parameter{
-			Type:  smartcontract.IntegerType,
-			Value: 1024 * 256,
-		})
+		checkResult(t, res, stackitem.NewBigInteger(big.NewInt(1024*256)))
 		require.NoError(t, chain.persist())
 	})
 
 	t.Run("set", func(t *testing.T) {
 		res, err := invokeNativePolicyMethod(chain, "setMaxBlockSize", bigint.ToBytes(big.NewInt(102400)))
 		require.NoError(t, err)
-		checkResult(t, res, smartcontract.Parameter{
-			Type:  smartcontract.BoolType,
-			Value: true,
-		})
+		checkResult(t, res, stackitem.NewBool(true))
 		require.NoError(t, chain.persist())
 		res, err = invokeNativePolicyMethod(chain, "getMaxBlockSize")
 		require.NoError(t, err)
-		checkResult(t, res, smartcontract.Parameter{
-			Type:  smartcontract.IntegerType,
-			Value: 102400,
-		})
+		checkResult(t, res, stackitem.NewBigInteger(big.NewInt(102400)))
 		require.NoError(t, chain.persist())
 	})
 }
@@ -93,20 +78,14 @@ func TestFeePerByte(t *testing.T) {
 	t.Run("get, contract method", func(t *testing.T) {
 		res, err := invokeNativePolicyMethod(chain, "getFeePerByte")
 		require.NoError(t, err)
-		checkResult(t, res, smartcontract.Parameter{
-			Type:  smartcontract.IntegerType,
-			Value: 1000,
-		})
+		checkResult(t, res, stackitem.NewBigInteger(big.NewInt(1000)))
 		require.NoError(t, chain.persist())
 	})
 
 	t.Run("set", func(t *testing.T) {
 		res, err := invokeNativePolicyMethod(chain, "setFeePerByte", bigint.ToBytes(big.NewInt(1024)))
 		require.NoError(t, err)
-		checkResult(t, res, smartcontract.Parameter{
-			Type:  smartcontract.BoolType,
-			Value: true,
-		})
+		checkResult(t, res, stackitem.NewBool(true))
 		require.NoError(t, chain.persist())
 		n := chain.contracts.Policy.GetFeePerByteInternal(chain.dao)
 		require.Equal(t, 1024, int(n))
@@ -127,20 +106,14 @@ func TestBlockedAccounts(t *testing.T) {
 	t.Run("get, contract method", func(t *testing.T) {
 		res, err := invokeNativePolicyMethod(chain, "getBlockedAccounts")
 		require.NoError(t, err)
-		checkResult(t, res, smartcontract.Parameter{
-			Type:  smartcontract.ArrayType,
-			Value: []smartcontract.Parameter{},
-		})
+		checkResult(t, res, stackitem.NewArray([]stackitem.Item{}))
 		require.NoError(t, chain.persist())
 	})
 
 	t.Run("block-unblock account", func(t *testing.T) {
 		res, err := invokeNativePolicyMethod(chain, "blockAccount", account.BytesBE())
 		require.NoError(t, err)
-		checkResult(t, res, smartcontract.Parameter{
-			Type:  smartcontract.BoolType,
-			Value: true,
-		})
+		checkResult(t, res, stackitem.NewBool(true))
 
 		accounts, err := chain.contracts.Policy.GetBlockedAccountsInternal(chain.dao)
 		require.NoError(t, err)
@@ -148,10 +121,7 @@ func TestBlockedAccounts(t *testing.T) {
 		require.NoError(t, chain.persist())
 
 		res, err = invokeNativePolicyMethod(chain, "unblockAccount", account.BytesBE())
-		checkResult(t, res, smartcontract.Parameter{
-			Type:  smartcontract.BoolType,
-			Value: true,
-		})
+		checkResult(t, res, stackitem.NewBool(true))
 
 		accounts, err = chain.contracts.Policy.GetBlockedAccountsInternal(chain.dao)
 		require.NoError(t, err)
@@ -163,35 +133,23 @@ func TestBlockedAccounts(t *testing.T) {
 		// block
 		res, err := invokeNativePolicyMethod(chain, "blockAccount", account.BytesBE())
 		require.NoError(t, err)
-		checkResult(t, res, smartcontract.Parameter{
-			Type:  smartcontract.BoolType,
-			Value: true,
-		})
+		checkResult(t, res, stackitem.NewBool(true))
 		require.NoError(t, chain.persist())
 
 		// double-block should fail
 		res, err = invokeNativePolicyMethod(chain, "blockAccount", account.BytesBE())
 		require.NoError(t, err)
-		checkResult(t, res, smartcontract.Parameter{
-			Type:  smartcontract.BoolType,
-			Value: false,
-		})
+		checkResult(t, res, stackitem.NewBool(false))
 		require.NoError(t, chain.persist())
 
 		// unblock
 		res, err = invokeNativePolicyMethod(chain, "unblockAccount", account.BytesBE())
-		checkResult(t, res, smartcontract.Parameter{
-			Type:  smartcontract.BoolType,
-			Value: true,
-		})
+		checkResult(t, res, stackitem.NewBool(true))
 		require.NoError(t, chain.persist())
 
 		// unblock the same account should fail as we don't have it blocked
 		res, err = invokeNativePolicyMethod(chain, "unblockAccount", account.BytesBE())
-		checkResult(t, res, smartcontract.Parameter{
-			Type:  smartcontract.BoolType,
-			Value: false,
-		})
+		checkResult(t, res, stackitem.NewBool(false))
 		require.NoError(t, chain.persist())
 	})
 
@@ -205,10 +163,7 @@ func TestBlockedAccounts(t *testing.T) {
 		for _, acc := range accounts {
 			res, err := invokeNativePolicyMethod(chain, "blockAccount", acc.BytesBE())
 			require.NoError(t, err)
-			checkResult(t, res, smartcontract.Parameter{
-				Type:  smartcontract.BoolType,
-				Value: true,
-			})
+			checkResult(t, res, stackitem.NewBool(true))
 			require.NoError(t, chain.persist())
 		}
 
@@ -253,9 +208,8 @@ func invokeNativePolicyMethod(chain *Blockchain, method string, args ...interfac
 	return res, nil
 }
 
-func checkResult(t *testing.T, result *state.AppExecResult, expected smartcontract.Parameter) {
+func checkResult(t *testing.T, result *state.AppExecResult, expected stackitem.Item) {
 	require.Equal(t, vm.HaltState, result.VMState)
 	require.Equal(t, 1, len(result.Stack))
-	require.Equal(t, expected.Type, result.Stack[0].Type)
-	require.EqualValues(t, expected.Value, result.Stack[0].Value)
+	require.Equal(t, expected, result.Stack[0])
 }
diff --git a/pkg/core/state/notification_event.go b/pkg/core/state/notification_event.go
index 1818f4c7b..48027137d 100644
--- a/pkg/core/state/notification_event.go
+++ b/pkg/core/state/notification_event.go
@@ -4,7 +4,6 @@ import (
 	"errors"
 
 	"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"
@@ -26,7 +25,7 @@ type AppExecResult struct {
 	Trigger     trigger.Type
 	VMState     vm.State
 	GasConsumed int64
-	Stack       []smartcontract.Parameter
+	Stack       []stackitem.Item
 	Events      []NotificationEvent
 }
 
@@ -59,7 +58,7 @@ func (aer *AppExecResult) EncodeBinary(w *io.BinWriter) {
 	w.WriteB(byte(aer.Trigger))
 	w.WriteB(byte(aer.VMState))
 	w.WriteU64LE(uint64(aer.GasConsumed))
-	w.WriteArray(aer.Stack)
+	stackitem.EncodeBinaryStackItem(stackitem.NewArray(aer.Stack), w)
 	w.WriteArray(aer.Events)
 }
 
@@ -69,6 +68,14 @@ func (aer *AppExecResult) DecodeBinary(r *io.BinReader) {
 	aer.Trigger = trigger.Type(r.ReadB())
 	aer.VMState = vm.State(r.ReadB())
 	aer.GasConsumed = int64(r.ReadU64LE())
-	r.ReadArray(&aer.Stack)
+	item := stackitem.DecodeBinaryStackItem(r)
+	if r.Err == nil {
+		arr, ok := item.Value().([]stackitem.Item)
+		if !ok {
+			r.Err = errors.New("array expected")
+			return
+		}
+		aer.Stack = arr
+	}
 	r.ReadArray(&aer.Events)
 }
diff --git a/pkg/core/state/notification_event_test.go b/pkg/core/state/notification_event_test.go
index 5242b8544..7a24315ce 100644
--- a/pkg/core/state/notification_event_test.go
+++ b/pkg/core/state/notification_event_test.go
@@ -5,7 +5,6 @@ import (
 
 	"github.com/nspcc-dev/neo-go/pkg/internal/random"
 	"github.com/nspcc-dev/neo-go/pkg/internal/testserdes"
-	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/nspcc-dev/neo-go/pkg/vm"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
 )
@@ -26,7 +25,7 @@ func TestEncodeDecodeAppExecResult(t *testing.T) {
 		Trigger:     1,
 		VMState:     vm.HaltState,
 		GasConsumed: 10,
-		Stack:       []smartcontract.Parameter{},
+		Stack:       []stackitem.Item{},
 		Events:      []NotificationEvent{},
 	}
 
diff --git a/pkg/rpc/response/result/application_log.go b/pkg/rpc/response/result/application_log.go
index 2ae28d01f..9ecae405f 100644
--- a/pkg/rpc/response/result/application_log.go
+++ b/pkg/rpc/response/result/application_log.go
@@ -43,13 +43,17 @@ func NewApplicationLog(appExecRes *state.AppExecResult) ApplicationLog {
 	for _, e := range appExecRes.Events {
 		events = append(events, StateEventToResultNotification(e))
 	}
-
+	st := make([]smartcontract.Parameter, len(appExecRes.Stack))
+	seen := make(map[stackitem.Item]bool)
+	for i := range appExecRes.Stack {
+		st[i] = smartcontract.ParameterFromStackItem(appExecRes.Stack[i], seen)
+	}
 	return ApplicationLog{
 		TxHash:      appExecRes.TxHash,
 		Trigger:     appExecRes.Trigger.String(),
 		VMState:     appExecRes.VMState.String(),
 		GasConsumed: appExecRes.GasConsumed,
-		Stack:       appExecRes.Stack,
+		Stack:       st,
 		Events:      events,
 	}
 }