Macroporous silicon membranes, consisting of straight parallel pores with a diameter of 3.3μm and depth/width ratio >60, are used as microreactors for high efficiency hydrogen generation via steam reforming of ethanol. The inner walls of the pores were coated with Co3O3*ZnO catalyst film. The as-prepared reactors were fed with water-ethanol gas mixture and the effect of the reactor temperature and inlet flow rate on the H2 generation was studied. We observed a superior H2 generation efficiency in comparison with conventional microreactors.