We already demonstrated that glass microfabricated reactors we designed were suitable for the direct synthesis of hydrogen peroxide so that 10 wt% of hydrogen peroxide was obtained at room temperature (296 K), 1 MPa. Here we compared three types of catalyst Pd/Al2O3,Pd/TiO2 and Pd-Au/TiO2 using the reactor we developed and we tried to understand the difference among catalysts. The reactors enabled us to obtain kinetic data under higher hydrogen contents than 10% without the risk of explosion. Kinetics analysis indicated that the reaction proceeded via two major processes, hydrogen peroxide synthesis and its subsequent hydrogenation, and that the latter process determined the hydrogen peroxide concentration achievable. (C) 2014 Elsevier B.V. All rights reserved.