The degradation of formic acid (HCOOH), FA (a surrogate contaminant) using titanium dioxide (TiO2) and 1% Pt doped TiO2 electrodes, prepared by sol-gel methods, was investigated in a photoelectrocatalytic (PEC) system in order to determine the effect of Pt doping on the oxidation potential of TiO2. Pt doping shifts the position of band edge and therefore the direct and indirect oxidation potentials of TiO2 in PEC systems. As a result, the degradation of formic acid via the generation of hydrogen peroxide production on 1% Pt-TiO2 electrodes was much better than that on non-doped electrodes. The degradation of HCOOH was also examined with respect to the faradaic efficiency of this process. It was found that the 1% Pt-TiO2 photoanode had a 30% higher efficiency than that of non-doped TiO2 photoanodes.