The photochemical conversion of methane into methanol from H2O2 aqueous solution as well as the effect of the addition mode were studied. Direct addition of different amounts H2O2 leads to increasing methanol production at the first stage of the reaction. The excess of H2O2 would lead to the reactive oxygen species scavenging and the subsequent O2 production. It was also corroborated that extra hydroxyl radicals in the aqueous medium do not improve the formation of methanol but a noticeable increase in the formation of HCOOH with respect to methanol was evidenced. In contrast, dosing addition at relatively low rates leads to constant methane consumption towards methanol. Methanol formation would be in this case in equilibrium with further oxidation to HCOOH or CO2. This suggests that only a controlled constant availability of HO’s at low concentration can enhance the performance of methanol generation in the photochemical process.