NOVELTY - Reducing an unsaturated organic compound using hydrogen and a catalyst comprising a metal salt or complex, a nicotinamide cofactor and a nicotinamide cofactor dependent enzyme (NCDE) is new.    USE - The methods can be used for reducing unsaturated organic compounds such as, acetoin, 1,1-dimethoxyacetone, glycerone, acetophenone, 2-acetylfuran, hydroxy-acetone, 6-methyl-5-heptene-2-one, 5-norbornene-2-one, 2-heptanone, 8-oxo-2-nonanone, cyclopropyl methyl ketone, L-sorbose, 2,4,6/3,5-pentahydroxycyclohexanone, aldose, glyoxylate, pyruvate, acetoacetate, ethyl 4-chloroacetoacetate, ethyl 4-oxo-hexanoate, oxaloacetate, 2,5-diketo-D-gluconic acid, D-glucono-1,5-lactone, 5alpha-androstane-3,17-dione, androst-4-ene-3,17-dione, L-lactaldehyde, fructose, D-glyceraldehyde, orotate, 2-oxoglutarate, 3-hydroxypyruvate, glyoxylate or L-lysine.    ADVANTAGE - The catalysts can efficiently add H2 to an unsaturated organic compound. They can often selectively produce only one of the 2 possible enantiomeric isomers.    DETAILED DESCRIPTION - Reducing (A) an unsaturated organic compound comprises mixing the unsaturated organic compound and H2 in the presence of a catalyst to form a reduced organic product, where the catalyst comprises:    (a) a metal salt or complex;    (b) a nicotinamide cofactor; and    (c) a NCDE;    where:    (i) when the metal salt or complex is a platinum carbonyl cluster complex, the catalyst does not comprise a redox active dye; and    (ii) when the metal salt or complex is a rhodium phosphine complex, the NCDE is not a mixture of horse liver alcohol dehydrogenase (HLADH) and lactate dehydrogenase (LDH).    INDEPENDENT CLAIMS are also included for the following:    (1) reducing an unsaturated organic compound, comprising mixing the unsaturated organic compound and H2 in the presence of a catalyst to form a reduced organic product, where the catalyst comprises:    (a) an aqueous buffer solution having a pH of 6.5 - 9.0;    (b) a water-soluble metal salt or complex comprising iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, or copper;    (c) a nicotinamide cofactor comprising NAD+, NADH, NADP+, NADPH, or a mixture; and    (d) one NCDE classified under the EC system as an 1.x.1.y. class enzyme, where x is 1, 3, 4, 5 or 10;    (2) reducing an unsaturated organic compound, comprising:    (a) contacting H2 and a catalyst; and    (b) contacting an unsaturated organic compound with the catalyst to form a reduced organic product; where the catalyst is as in (A);    (3) reducing an unsaturated organic compound comprising:    (a) contacting H2, at least one metal salt or complex, and at least one nicotinamide cofactor to form at least some reduced nicotinamide cofactor; and    (b) contacting the reduced nicotinamide cofactor, a NCDE, and an unsaturated organic compound to form at least some of a reduced organic product; where:    (i) when the metal salt or complex is a platinum carbonyl cluster complex, the catalyst does not comprise a redox active dye; and    (ii) when the metal salt or complex is a rhodium phosphine complex the NCDE is not a mixture of HLADH and LDH;    (4) a process comprising adding dihydrogen, H2, to an unsaturated organic substrate using as a catalyst a mixture comprising an enzyme, a nicotinamide cofactor, a metal salt or complex and optionally ligands, where the metal of the metal salt or complex is selected from iron, cobalt, nickel, copper, ruthenium, palladium, osmium, and iridium;    (5) a composition for reducing unsaturated organic compounds comprising H2 and a catalyst, the catalyst comprising:    (a) at least one metal salt or complex;    (b) at least one nicotinamide cofactor; and    (c) a NCDE; where:    (i) when the metal salt or complex is a platinum carbonyl cluster complex, the catalyst does not comprise a redox active dye; and    (ii) when the metal salt or complex is a rhodium phosphine complex, the NCDE is not a mixture of HLADH and LDH; and    (6) stabilizing the activity of an oxidoreductase enzyme, comprising mixing a phosphine or phosphite with an oxidoreductase enzyme.