The photocatalytic thermodynamic efficiency factor (PTEF) is a parameter that can be used in photocatalytic reactors to establish photon energy utilization as the ratio of the energy used to generate OH center dot free radicals and the energy absorbed by the TiO2 photocatalyst. The PTEF evaluation requires the assessment of the total rate of OH center dot free radicals at any given time during the photoconversion of organic species. A key parameter in this assessment is the availability of the complete spectrum of measurable chemical species including various intermediates. Quantification of different chemical species and their evolution with irradiation time allow via stoichiometric relationships the calculation of the OH center dot radicals consumed in the photocatalytic reactor. PTEFs and quantum yields (QY) were reported recently for phenol photocatalytic conversion in water media (free of iron ions) displaying 71% and 19% maximum QYs and PTEFs, respectively.(19) In the present study, the QY and PTEF are reviewed further, considering the photoconversion of phenol in water media enhanced by iron ions. It is shown using the more realistic RN2 model that the maximum QYs and PTEFs reach up to 85% and 23% levels, respectively. These encouraging efficiency factors demonstrate the favorable prospects of photocatalysis and Photo-CREC Water reactors operated under optimum photocatalyst loading conditions (0.14 g/L), with only a small fraction of the total absorbed photons potentially lost in photon recombination.