Hydrogen peroxide (H2O2) is an effective oxidizing agent that is commonly used in industry. In the presence of metal catalysts, H2O2 can decompose into water and oxygen. Understanding this process at a fundamental level is extremely important for a number of industrial applications, e.g. the direct synthesis of H2O2 from H-2 and O-2. Here, we studied the rates of H2O2 decomposition on Pt/n-Si catalysts using a chemicurrent approach that is based on the detection of hot electrons created during dissociative adsorption of H2O2 molecules on platinum. We showed that both the rate of H2O2 decomposition and the corresponding chemicurrent are sensitive to the pH of the reactive solution. This phenomenon is explained by variation of the potential barrier for electron transfer at the Pt/solution interface caused by adsorption of H+ and OH- species from the solution on the catalytic surface.