A novel electrochemical microactuator made with the use of silicon micromachining techniques, and its feasibility, are presented. Gas pressure is generated by electrolysis of an aqueous electrolyte solution. The pressure built up is used to change the deflection of a membrane. The actuator has three states: the electrolysis state, in which the pressure is built up; the passive state, in which the circuit is open and the pressure is maintained; and the pressure reduction state, in which the electrodes are short-circuited in order to reverse the electrolysis reaction. The advantage of this type of actuation is a relatively large pressure generation with low energy consumption. Power is required only for pressure build-up and for changing the states. Therefore, this type of actuation has promising applications in pumps or active valves.