The current status of absorption cross-section measurements for aeronomic use is reviewed. Recommended values for the gases O2, N2, O, and O3 are given at wavelengths where there is strong atmospheric absorption in the 3500–10 Å region. A table of absorption and ionization cross-sections at important solar emission lines is given. The problem of insufficient resolution at some wavelengths is discussed, and information on photolysis products is given where available.