[en] The gain spectrum of a high-pressure uv preionized CO2 laser was measured for pressures to 14 atm. The data show an approx.10% increase in the gain of the P branch of the 961-cm/sup -1/ (00degree1) - (10degree0)1 band which is attributed to the overlapping 927-cm/sup -1/ 0111- (1110)1 band. The measured gain was shown to be in good agreement with the theoretical predictions of a four-temperature kinetic model