diff --git a/cairo/ethereum/cancun/vm.cairo b/cairo/ethereum/cancun/vm.cairo
index 09b774e6..d914aed0 100644
--- a/cairo/ethereum/cancun/vm.cairo
+++ b/cairo/ethereum/cancun/vm.cairo
@@ -297,7 +297,7 @@ namespace EvmImpl {
         return ();
     }
 
-    func set_refund_counter{evm: Evm}(new_refund_counter: Uint) {
+    func set_refund_counter{evm: Evm}(new_refund_counter: felt) {
         tempvar evm = Evm(
             new EvmStruct(
                 pc=evm.value.pc,
diff --git a/cairo/ethereum/cancun/vm/instructions/storage.cairo b/cairo/ethereum/cancun/vm/instructions/storage.cairo
index 42aa6f37..3ab5c0c9 100644
--- a/cairo/ethereum/cancun/vm/instructions/storage.cairo
+++ b/cairo/ethereum/cancun/vm/instructions/storage.cairo
@@ -1,8 +1,8 @@
 from ethereum.cancun.vm.stack import pop, push
 from ethereum.cancun.vm import Evm, EvmImpl, Environment, EnvImpl
-from ethereum.cancun.vm.exceptions import ExceptionalHalt
+from ethereum.cancun.vm.exceptions import ExceptionalHalt, WriteInStaticContext, OutOfGasError
 from ethereum.cancun.vm.gas import charge_gas, GasConstants
-from ethereum.cancun.state import get_storage
+from ethereum.cancun.state import get_storage, get_storage_original, set_storage
 from ethereum.cancun.fork_types import (
     SetTupleAddressBytes32,
     SetTupleAddressBytes32DictAccess,
@@ -21,6 +21,7 @@ from starkware.cairo.common.cairo_builtins import PoseidonBuiltin, BitwiseBuilti
 from starkware.cairo.lang.compiler.lib.registers import get_fp_and_pc
 from starkware.cairo.common.alloc import alloc
 from starkware.cairo.common.dict_access import DictAccess
+from starkware.cairo.common.math_cmp import is_le
 
 // @notice Loads to the stack the value corresponding to a certain key from the
 // storage of the current account.
@@ -95,3 +96,127 @@ func sload{range_check_ptr, bitwise_ptr: BitwiseBuiltin*, poseidon_ptr: Poseidon
     let ok = cast(0, ExceptionalHalt*);
     return ok;
 }
+
+// @notice Stores a value at a certain key in the current context's storage.
+func sstore{
+    range_check_ptr, bitwise_ptr: BitwiseBuiltin*, poseidon_ptr: PoseidonBuiltin*, evm: Evm
+}() -> ExceptionalHalt* {
+    alloc_locals;
+    // STACK
+    let stack = evm.value.stack;
+    with stack {
+        let (key, err) = pop();
+        if (cast(err, felt) != 0) {
+            return err;
+        }
+        let (new_value, err) = pop();
+        if (cast(err, felt) != 0) {
+            return err;
+        }
+    }
+
+    let is_gas_left_not_enough = is_le(evm.value.gas_left.value, GasConstants.GAS_CALL_STIPEND);
+    if (is_gas_left_not_enough != 0) {
+        tempvar err = new ExceptionalHalt(OutOfGasError);
+        return err;
+    }
+
+    // Get storage values
+    let key_bytes32 = U256_to_be_bytes(key);
+    let state = evm.value.env.value.state;
+    let current_target = evm.value.message.value.current_target;
+    with state {
+        let original_value = get_storage_original(current_target, key_bytes32);
+        let current_value = get_storage(current_target, key_bytes32);
+    }
+
+    // Gas calculation
+    // Check accessed storage keys
+    tempvar accessed_tuple = TupleAddressBytes32(
+        new TupleAddressBytes32Struct(current_target, key_bytes32)
+    );
+    let (serialized_keys: felt*) = alloc();
+    assert serialized_keys[0] = accessed_tuple.value.address.value;
+    assert serialized_keys[1] = accessed_tuple.value.bytes32.value.low;
+    assert serialized_keys[2] = accessed_tuple.value.bytes32.value.high;
+    let dict_ptr = cast(evm.value.accessed_storage_keys.value.dict_ptr, DictAccess*);
+    with dict_ptr {
+        let (is_present) = hashdict_read(3, serialized_keys);
+        if (is_present == 0) {
+            hashdict_write(3, serialized_keys, 1);
+            tempvar gas_cost = GasConstants.GAS_COLD_SLOAD;
+            tempvar poseidon_ptr = poseidon_ptr;
+            tempvar dict_ptr = dict_ptr;
+        } else {
+            tempvar gas_cost = 0;
+            tempvar poseidon_ptr = poseidon_ptr;
+            tempvar dict_ptr = dict_ptr;
+        }
+    }
+    let gas_cost = [ap - 3];
+    let poseidon_ptr = cast([ap - 2], PoseidonBuiltin*);
+    let dict_ptr = cast([ap - 1], DictAccess*);
+
+    // Calculate storage gas cost
+    if (original_value.value == current_value.value) {
+        if (current_value.value != new_value.value) {
+            if (original_value.value == 0) {
+                tempvar gas_cost = gas_cost + GasConstants.GAS_STORAGE_SET;
+            } else {
+                tempvar gas_cost = gas_cost + (
+                    GasConstants.GAS_STORAGE_UPDATE - GasConstants.GAS_COLD_SLOAD
+                );
+            }
+        }
+    } else {
+        tempvar gas_cost = GasConstants.GAS_WARM_ACCESS;
+    }
+    let gas_cost = [ap - 1];
+
+    tempvar refund_counter = evm.value.refund_counter;
+    // Refund calculation
+    if (current_value.value != new_value.value) {
+        if (original_value.value != 0 and current_value.value != 0 and new_value.value == 0) {
+            // Storage cleared for first time
+            refund_counter = refund_counter + GasConstants.GAS_STORAGE_CLEAR_REFUND;
+        }
+        if (original_value.value != 0 and current_value.value == 0) {
+            // Reverse previous refund
+            refund_counter = refund_counter - GasConstants.GAS_STORAGE_CLEAR_REFUND;
+        }
+        if (original_value.value == new_value.value) {
+            if (original_value.value == 0) {
+                refund_counter = refund_counter +
+                    (GasConstants.GAS_STORAGE_SET - GasConstants.GAS_WARM_ACCESS);
+            } else {
+                refund_counter = refund_counter +
+                    (GasConstants.GAS_STORAGE_UPDATE - GasConstants.GAS_COLD_SLOAD - GasConstants.GAS_WARM_ACCESS);
+            }
+        }
+    }
+
+    // Charge gas
+    let err = charge_gas(Uint(gas_cost));
+    if (cast(err, felt) != 0) {
+        return err;
+    }
+    // Check static call
+    if (evm.value.message.value.is_static.value != 0) {
+        tempvar err = new ExceptionalHalt(WriteInStaticContext);
+        return err;
+    }
+
+    // Set storage
+    with state {
+        set_storage(current_target, key_bytes32, new_value);
+    }
+
+    // Update EVM state
+    let env = evm.value.env;
+    EnvImpl.set_state{env=env}(state);
+    EvmImpl.set_env(env);
+    EvmImpl.set_pc_stack(Uint(evm.value.pc.value + 1), stack);
+    EvmImpl.set_refund_counter(refund_counter);
+    let ok = cast(0, ExceptionalHalt*);
+    return ok;
+}
diff --git a/cairo/tests/ethereum/cancun/vm/instructions/test_storage.py b/cairo/tests/ethereum/cancun/vm/instructions/test_storage.py
index dc212422..c2d40824 100644
--- a/cairo/tests/ethereum/cancun/vm/instructions/test_storage.py
+++ b/cairo/tests/ethereum/cancun/vm/instructions/test_storage.py
@@ -7,7 +7,7 @@
 from hypothesis import strategies as st
 from hypothesis.strategies import composite
 
-from ethereum.cancun.vm.instructions.storage import sload
+from ethereum.cancun.vm.instructions.storage import sload, sstore
 from tests.utils.args_gen import Evm
 from tests.utils.evm_builder import EvmBuilder
 from tests.utils.strategies import MAX_STORAGE_KEY_SET_SIZE
@@ -46,3 +46,14 @@ def test_sload(self, cairo_run, evm: Evm):
 
         sload(evm)
         assert evm == cairo_evm
+
+    @given(evm=evm_with_accessed_storage_keys())
+    def test_sstore(self, cairo_run, evm: Evm):
+        try:
+            cairo_evm = cairo_run("sstore", evm)
+        except Exception as cairo_error:
+            with pytest.raises(type(cairo_error)):
+                sstore(evm)
+            return
+        sstore(evm)
+        assert evm == cairo_evm