Hydrogenation of monofunctional (olefinic and carbonyl) and bifunctional (alpha, beta-unsaturated aldehyde compounds have been studied over cobalt borides. The cobalt borides P-1Co and P-2WCo were prepared by reducing cobalt acetate with sodium borohydride in aqueous and 50% ethanolic media, respectively. P-1Co is more active than P-2WCo for hydrogenation of olefinic groups, whereas P-1Co is less active for carbonyl groups. Chromium and molybdenum effectively promote P-1Co and P-2WCo in carbonyl group reduction, but chromium depresses P-1Co and P-2WCo on olefinic group reduction. P-1Co and P-2WCo can selectively reduce benzene to cyclohexene and alpha,beta-unsaturated aldehyde to unsaturated alcohol, reactions that are difficult on other heterogeneous catalysts.