Abstract: A microchannel reactor is disclosed that provides superior performance for three-phase (gas/liquid/solid-catalyst) reactions. The reactor may be used, for example, in industrial-scale catalysis, e.g., in large-scale chemical production, and also in catalyst screening. Each microchannel in the reactor has a separate micro-outlet to supply gas to the channel. Each microchannel is open on both ends, so that liquid may freely flow through the channels in both directions. Oscillatory forcing is applied to the liquid outside the microreactor. The combined effect of the separate gas inlets for each microchannel, the open nature of the microchannels on both ends, and oscillatory forcing results in highly efficient transport of both gas and liquid through all of the microchannels, promotes efficient mixing, and enhances catalysis.