This study involves a novel method for immobilized enzyme catalysis. The focus of the work was to design and construct a microscale bioreactor using microfabrication techniques traditionally employed within the semiconductor industry. Enzymes have been immobilized on the microreactor walls by incorporating them directly into the wall material. Fabricated microchannels have cross-sectional dimensions on the order of hundreds of micrometers, constructed using polydimethylsiloxane cast on silicon/SU-8 molds. The resulting ratio of high surface area to volume creates an efficient, continuous-flow reaction system. Transverse features also containing enzymes were molded directly into the channels.