Lasing characteristics of an 80 mm-bore copper vapor laser (CVL) are investigated experimentally to increase the laser output power and efficiency. The experiment is carried out at a constant temperature of the CVL discharge tube. It is found that the laser output power increases proportionally to the discharge voltage across the plasma in the CVL discharge tube and that the discharge voltage is more important for the increase of laser output power than the population density of the metastable lower laser level. Higher discharge voltage is obtained with a buffer gas of neon and hydrogen mixture rather than with neon gas only. This suggests that hydrogen is effective to increase the recombination rate of the charged particles. A laser output power of 210 W is obtained with the mixed buffer gas by applying the excitation pulses of 5 kHz to 80 mm-bore discharge tube of 2.1 m discharge length.