The direct synthesis of hydrogen peroxide from molecular H2 and O2 represents a green and economic alternative to the current anthraquinone process used for the industrial production of H2O2. In order for the direct process to compete with the anthraquinone process, there is a need for enhanced H2O2 yields and H2 selectivity in the process. We show that Au–Pd-exchanged and supported Cs-containing heteropolyacid catalysts with the Keggin structure are considerably more effective in achieving high H2O2 yields in the absence of acid or halide additives than previously reported catalysts. The Au–Pd-exchanged Cs-heteropolyacid catalysts also show superior H2O2 synthesis activity under challenging conditions (ambient temperature, water-only solvent and CO2-free reaction gas). Au plays a crucial role in achieving the improved performance of these heteropolyacid-based catalysts. The heteropolyacid limits the subsequential hydrogenation/decomposition of H2O2.