There is an increasing interest in the research and application of biomass-based wood hydrolysates. Wood hydrolysates, in addition to using fuel, are also a chemical source with several organic compounds. In this study, fungicidal and termiticidal properties of wood hydrolysates from biomass slurry fuel (BSF) production using sugi (Cryptomeria japonica) and acacia (Acacia mangium) wood were evaluated in laboratory decay and termite resistance tests. Wood specimens treated with wood hydrolysates showed increased resistance against brown-rot fungus Fomitopsis palustris. However wood hydrolysates from sugi wood processed at 270 degrees C which contained less phenolic compounds than the other hydrolysates were effective against white-rot fungus Trametes versicolor. Thus, phenolic compounds of wood hydrolysates seem to play an important role in the decay resistance tests. Wood hydrolysates did not increase the durability of the wood block against subterranean termites Coptotermes formosanus. Despite high acetic and lactic acid content of the wood hydrolysates, vanillin content of wood hydrolysates may have served as an additional food source and promoted termite attack. It can be concluded that wood hydrolysates with phenolic compounds from lignin degradation during BSF production can be considered for targeted inhibition of brown-rot.