Chemical utilization of the photoproducts has been accomplished by the introduction of synthetic catalysts or natural enzymes into the photochemical systems. With Ru(NH//3)//5Cl**2** plus as electron acceptor and catalyst the photocleavage of acetylene (C//2H//2) to methane is observed. This process is a 6-electron reduction process and offers a model for the N//2-fixation reaction. Also, by the introduction of the enzyme ferredoxin reductase, a photochemical NADPH regeneration cycle has been established. The NADPH has been utilized in the reduction of ketones to alcohols in the presence of a secondary enzyme, alcohol dehydrogenase.