Absolute photoelectric yields of Pt and Ta and photoionization yields in O2 and N2 are reported for the spectral region from 436 to 1004 angstroms. The experimental methods as well as the monochromator, light source and associated apparatus are described. The results for Pt and Ta give photoelectric yields between 10-1 and 10-2 electron per photon for wavelengths shorter than 1000A. These values are 10 to 100 times larger than those obtained for the same metals between 2000A and 3000A. Photoionization results for O2 indicate that below 700A almost all absorbed photons produce ion pairs, while in the region between 700A and the first ionization limit at 1000A the yield varies rapidly. In the case of N2 at wavelengths shorter than 796A, its first ionization limit, the yield rises steeply. Below 725A almost all absorbed photons produce ion pairs. The over‐all error is estimated to be within ±20 percent.