The paper describes a three-electrode electric-discharge XeC1 -laser, in which the discharge ignition takes place, when a highvoltage pulse is delivered to a middle control electrode, a capacitor bank of the main discharge is connected directly to two other electrodes. The three-electrode system of a double discharge formation provides a sequential in time breakdown of two discharge gaps followed by a general discharge current The laser reached the high efficiency up to 3.7 % with the fast commutation < 5 % from the pump energy and a significant decrease of the load on the elements of the electric system of the laser power supply.