Measurements of molecular oxygen in the approximate altitude region 110--170 km were obtained from two rocket flights of a solar-pointed 1450-¿ photometer launched from White Sands Missile Range, New Mexico, when the geomagnetic index Kp at 6.7 hours prior to launch was 1.5 and 4.2 . For Kp of 1.5 the densities predicted by the Jacchia (1971) model atmosphere agree with the experimental densities near 135 km, are low by about 20% for altitudes below 130 km, and are high above 135 km by amounts increasing from 15% at 140 km to 50% at 160 km. For Kp of 4.2 the model densities are consistently higher than the experimental densities by as much as 50% over the altitude range of the measurements, except for a narrow region near 120 km where an enhancement in the density causes close agreement between the model and experimental densities. At the particular altitude of 150 km, identical O2 densities of 1.95¿109 cm-3 were obtained for the two levels of Kp of 1.5 and 4.2. These measurements are compared with recent measurements by others.