Resorcinol-lactose resin was synthesized using phosphoric acid as the catalyst at 95degreesC. C-13-NMR measurements proved that the chemical reaction is initiated at the 4- or 6-carbon position in benzene ring. Sample separation by size-exclusion chromatography (SEC) technology indicated that the resin consists of reacting mixtures of oligomer of lactose, glucose, and galacose with resorcinol. The resin, using a by product of diary industry as a main component, could be potentially applied as a novel adhesive to the wood process industry.