Applying a damped oscillating discharge to a dielectric‐electrode TE (transversely excited) CO2laser, we obtain a high‐power and long‐pulse CO2laser output. With a decreasing value of the inductance inserted in parallel with the discharge load so as to make the discharge condition damped oscillating, laser output energy increased remarkably. When the inductance was 500 nH, a uniform glow discharge was obtained up to gas pressures of 500–600 Torr without any preionization. At a total pressure of 700 Torr (CO2/N2/He=1/2/8), a maximum CO2laser output energy of 270 mJ/pulse (7.3 J/l atm) was obtained with an electrical efficiency of 4.3% and with a pulse duration of 7 &mgr;s.