Certain urea-sulfuric acid components, comprised of urea and sulfuric acid in a 1/4 to 7/4 molar ratio, contain a monourea adduct of sulfuric acid, which is catalytically active for promoting organic chemical reactions. The invention provides methods employing such urea-sulfuric acid components for catalyzing organic reactions such as oxidation, oxidative addition, reduction, reductive addition, esterification, transesterification, hydrogenation, isomerization (including racemization of optical isomers), alkylation, polymerization, demetallization of organometallics, nitration, Friedel-Crafts reactions, and hydrolysis. Novel catalysts are disclosed which involve combinations of the urea-sulfuric component with one or more transition metal halides and/or with one or more surfactants. The surfactant-containing compositions are particularly useful for the treatment of materials containing lipophilic substances. Novel compositions containing the urea-sulfuric acid component and one or more organic reactants are also disclosed.