The present study reports photochemical thermodynamic efficiency factors (PTEFs) for hydrogen production. The PTEF parameter equates the enthalpy of formation of consumed OH center dot and H-center dot free radicals with their absorbed photon energy. In this case, therefore, the PTEFs provide information on the efficiency of photon energy utilization. Data from different Pt- and Pd-doped photocatalysts used for hydrogen production, obtained in a Photo-CREC Water-II reactor under near-UV and visible irradiations, were considered. The evaluated photocatalysts were characterized using X-ray diffraction (XRD), the Brunauer-Emmett-Teller (BET) method, chemisorption, and diffuse reflectance UV-visible spectroscopy. Macroscopic radiation energy balances and the rates of photoconversion of hydrogen were also determined to evaluate both PTEFs and quantum yields (phi). While PTEFs were reported previously by our research group for water and air decontamination, the PTEF is now applied, for the first time, in this research, to hydrogen production.