The photoionization of propiophenone via two different routes was investigated by single-pulse and two-pulse laser-flash photolysis with observation of the hydrated electron and the respective photoionizable intermediate, the triplet or the radical anion. From the dependences of the absolute concentrations on the excitation intensity, kinetic constants and quantum yields were obtained. In the presence of a large surplus of a sacrificial electron donor (triethylamine or DABCO), the reaction is cyclic, with the radical anion of the ketone first formed by photoinduced electron transfer, and then ionized by another photon to regenerate the starting material, all within the same laser flash. The quantum yield of photoionization of the radical anion is 0.25 at 308 nm. In the absence of a donor, the ketone triplet is ionized. The intensity dependences indicate a more complex mechanism than a consecutive reaction and provide evidence for an additional photoreaction of the triplet, presumably regeneration of the starting material by reverse intersystem crossing via a chemical pathway. The quantum yield of photoionization of the triplet is 0.05 at 308 nm and 0.02 at 355 nm. As the electronic configurations of the autoionizing upper excited states are very similar, it is proposed that the lower quantum yield in the case of the triplet might be due to competing deactivation channels, which are not open to the upper excited radical anion.