The approach of producing hydrogen peroxide (H2O2) by direct catalyzed reaction of H-2 and O-2 has been extensively studied over the past decades. The process offers the potential to establish a "green" alternative to the conventional large-scale anthraquinone process. However, the implementation of this reaction still faces major hurdles including safety, selectivity and productivity of the reaction. In this work, we report results on the development of a novel intensified suspension-flow membrane micro reactor system for direct synthesis of hydrogen peroxide as well as on a related flexible micro reactor system for transfer hydrogenation which served as a starting point. In the new reactor system for H2O2 direct synthesis safety issues are greatly reduced by the introduction of a membrane to separate the gaseous reactants. Furthermore productivity is maximized by increased mass transfer in micro channels and constant reactant feeding over the length of the reactor. Finally, the selectivity can be optimized by controlling the reactant distribution in the liquid phase. A rigorous two-dimensional single-phase model based on ANSYS Fluent was adopted to study the influence of the design on the reaction. This model had already been validated in a previous study. By expanding the model to describe the multiphase phenomena we were able to get further insight on the behavior of the overall system. (C) 2016 Elsevier B.V. All rights reserved.