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Over the years, biocatalysis has evolved as an extremely useful tool for synthetic applications due to the incredible selectivity it offers under relatively mild reaction conditions. With the advent of directed evolution and enzyme engineering, new reactivities previously unknown in nature are also being discovered by scientists. One of the main factors that determines the cost and efficiency of many biocatalytic reactions is their cofactor regeneration system. Cofactors are helper molecules that aid an enzyme to sustain catalysis. Their complex structure makes them prohibitively expensive such that their stoichiometric addition for a biocatalytic reaction is not viable. Cofactor regeneration involves the recycling of a catalytic quantity of the cofactor over and over again using a catalyst. Cofactor regeneration techniques for the nicotinamide cofactors have been widely resolved in the past to an extent that some enzymes dependent on these cofactors have found application in industry. This thesis looks at ways to recycle another useful class of cofactors - the flavins. Preliminary efforts to regenerate the deazaflavin cofactors are also presented. Enzymes that rely on flavin cofactors have valuable synthetic utility, however, their application in industry is not well established perhaps due to the lack of efficient recycling methods. This project resulted in an exciting discovery that hydrogenases can reduce flavins under H2, an atom economical reductant. The robust nature and exceptional stability of the hydrogenase, Hyd1 was exploited to supply reduced flavins for ene-reductases and nitroreductases to accomplish H2-driven C=C double bond reductions and nitro reductions respectively with high selectivity. Thus a new application for the hydrogenase enzyme has been uncovered. Demonstration of this novel, single-enzyme flavin regeneration system for application with several useful enzymes, with benefits over current flavin recycling methods, could make this Hyd1/ flavin system a promising choice for use in industry.