diff --git a/contracts/sfc/Staker.sol b/contracts/sfc/Staker.sol
index c26f0d0..3be11ce 100644
--- a/contracts/sfc/Staker.sol
+++ b/contracts/sfc/Staker.sol
@@ -71,6 +71,13 @@ contract Stakers is Ownable, StakersConstants {
         uint256 stakeTotalAmount;
         uint256 delegationsTotalAmount;
         uint256 totalSupply;
+        uint256 totalLockedAmount;
+    }
+
+    struct LockedAmount {
+        uint256 fromEpoch;
+        uint256 startTime;
+        uint256 endTime;
     }
 
     uint256 private reserved1;
@@ -140,6 +147,9 @@ contract Stakers is Ownable, StakersConstants {
 
     mapping(address => mapping(uint256 => WithdrawalRequest)) public withdrawalRequests;
 
+    uint256 public firstLockedUpEpoch;
+    mapping(uint256 => LockedAmount) public lockedStakes; // stakerID -> LockedAmount
+
     /*
     Getters
     */
@@ -408,6 +418,17 @@ contract Stakers is Ownable, StakersConstants {
             return 0; // avoid division by zero
         }
         uint256 weightedTotalStake = stake.add((delegatedTotal.mul(commission)).div(RATIO_UNIT));
+
+        if (firstLockedUpEpoch > 0 && epoch >= firstLockedUpEpoch) {
+            if (lockedStakes[stakerID].fromEpoch >= epoch && epochSnapshots[epoch.sub(1)].endTime > lockedStakes[stakerID].endTime) {
+                uint256 totalLockedAmount = epochSnapshots[epoch].totalLockedAmount;
+                uint256 lockedReward = rawReward.mul(RATIO_UNIT - unlockedRatio()).div(RATIO_UNIT).mul(weightedTotalStake).div(totalLockedAmount);
+                rawReward = (rawReward.mul(unlockedRatio()).div(RATIO_UNIT)).add(lockedReward);
+            } else {
+                rawReward = rawReward.mul(unlockedRatio()).div(RATIO_UNIT);
+            }
+        }
+
         return (rawReward.mul(weightedTotalStake)).div(totalStake);
     }
 
@@ -584,6 +605,7 @@ contract Stakers is Ownable, StakersConstants {
         require(stakers[stakerID].stakeAmount != 0, "staker doesn't exist");
         require(stakers[stakerID].deactivatedTime == 0, "staker is deactivated");
         require(stakers[stakerID].paidUntilEpoch == currentSealedEpoch, "not all rewards claimed"); // for rewards burning
+        require(lockedStakes[stakerID].fromEpoch == 0 || lockedStakes[stakerID].endTime > block.timestamp, "stake is locked");
 
         _mayBurnRewardsOnDeactivation(false, stakerID, stakerSfcAddr, stakers[stakerID].stakeAmount, stakers[stakerID].stakeAmount);
 
@@ -601,6 +623,7 @@ contract Stakers is Ownable, StakersConstants {
         require(stakers[stakerID].stakeAmount != 0, "staker doesn't exist");
         require(stakers[stakerID].deactivatedTime == 0, "staker is deactivated");
         require(stakers[stakerID].paidUntilEpoch == currentSealedEpoch, "not all rewards claimed"); // for rewards burning
+        require(lockedStakes[stakerID].fromEpoch == 0 || lockedStakes[stakerID].endTime > block.timestamp, "stake is locked");
         require(amount >= minStakeDecrease(), "too small amount"); // avoid confusing wrID and amount
 
         // don't allow to withdraw full as a request, because amount==0 originally meant "not existing"
@@ -804,6 +827,27 @@ contract Stakers is Ownable, StakersConstants {
         emit UpdatedBaseRewardPerSec(value);
     }
 
+    function startLockedUp(uint256 epochNum) onlyOwner external {
+        if (epochNum > 0) {
+            firstLockedUpEpoch = epochNum;
+        }
+    }
+
+    function lockUpStake(uint256 lockDuration) external {
+        uint256 stakerID = _sfcAddressToStakerID(msg.sender);
+        require(stakers[stakerID].stakeAmount != 0, "staker doesn't exist");
+        require(stakers[stakerID].deactivatedTime == 0, "staker is deactivated");
+        require(lockDuration >= 86400 * 14 && lockDuration <= 86400 * 365, "incorrect duration");
+        require(lockedStakes[stakerID].endTime > block.timestamp.add(lockDuration), "stake already locked up");
+        require(firstLockedUpEpoch == 0 || firstLockedUpEpoch > currentSealedEpoch, "feature was not activated");
+//        require(stakers[stakerID].paidUntilEpoch == currentSealedEpoch, "not all rewards claimed"); // for rewards burning
+        LockedAmount memory lStake = LockedAmount(
+            currentSealedEpoch,
+            block.timestamp,
+            block.timestamp.add(lockDuration));
+        lockedStakes[stakerID] = lStake;
+    }
+
     event UpdatedDelegation(address indexed delegator, uint256 indexed oldStakerID, uint256 indexed newStakerID, uint256 amount);
 
     // syncDelegator updates the delegator data on node, if it differs for some reason
diff --git a/contracts/sfc/StakerConstants.sol b/contracts/sfc/StakerConstants.sol
index 169a01f..1d5d1ef 100644
--- a/contracts/sfc/StakerConstants.sol
+++ b/contracts/sfc/StakerConstants.sol
@@ -74,6 +74,13 @@ contract StakersConstants {
         return (30 * RATIO_UNIT) / 100; // 30%
     }
 
+    /**
+     * @dev The ratio of the reward rate at base rate (no lock), e.g., 30%
+     */
+    function unlockedRatio() public pure returns (uint256) {
+        return (30 * RATIO_UNIT) / 100; // 30%
+    }
+
     /**
      * @dev the period of time that stake is locked
      */