The photoionization and dissociative photoionizations of propylene oxide have been studied both experimentally and theoretically. In experiments, photoionization efficiency spectra for ions C3H6O+, C2H3O+, CH3O+, CH2O+, CHO+, C2H4+, C2H3+, C2H2+, CH3+, and CH2+ were obtained. Theoretically, the energetics of the dissociative photoionizations were examined by ab initio Gaussian-2 calculations. The computational results are useful in our attempt to establish the dissociation channels near the ionization thresholds. The dissociation channels we propose include simple bond cleavage reactions as well as reactions involving intermediates and transition structures.