The electronic UV absorption spectra of thermal reaction products H-Xe-Y (Y = Cl, Pr, I, or CN) have been measured in solid Xe at 12 K. The spectra are obtained after the annealing of an extensively irradiated matrix doped with an HCl, HBr, HI, or HCN precursor. The spectral assignment is based on the correlation between the UV spectra and the known infrared absorptions of these compounds. An analysis of the annealing behavior of the UV absorptions due to H-Xe-Y, Y/Xe and H/Xe yields a quantitative estimate that 20-30% of the photogenerated Y is converted to H-Xe-Y. Present multireference configuration interaction (MRCI) calculations provide strong support that the spectral observations are due to the A (1)Sigma <-- X (1) transitions of H-Xe-Y. The spectral width of the absorptions indicate that the transitions are from a bound ground state to a repulsive excited state.