Foam offers an appropriate surface to perform lipase-mediated reactions. Aqueous foam, a colloidal dispersion of air in water, offers a very high substrate surface to solvent volume ratio for lipases to act. Esterification, an unfavorable reaction in prater, could be efficiently done by lipase in aqueous foams made of lipase substrates. Esterification of oleic acid with a homologous series of aliphatic alcohols of varying length showed that surface excess property of both the substrates is essential for ester formation. The direction of lipase reaction is governed by the composition of the reactants in the interface. Similar reactions could be done in water with substrates adsorbed on hydrophobic beads. Foam-based reactions offer a simple, cheaper and environment-friendly method to conduct lipase-mediated reactions.