Some chemical properties and lignin-related phenolic acids were measured in tropical uncultivated and cultivated Malaysian peats and compared with those of a subfrigid uncultivated Japanese peat. The phenolic acids were identified by gas-liquid chromatography combined with mass spectrometry and determined by gas-liquid chromatography. The total amount of phenolic acids was 13 to 14 mg/g soil C in the Malaysian peat, similar to the 11 mg/g soil C in the Japanese peat. The ratio of the total amounts of substituted hydroxybenzoic acids, viz. 4-hydroxybenzoic + vanillic + syringic to substituted hydroxycinnamic acids, viz.p-coumaric + ferulic, was smaller in the tropical peat soils than in the subfrigid peat. Sinapic acid was not detected in any of the peats. The effect of a laccase fromTrametes versicoloron these phenolic acids was determined. The substituted hydroxycinnamic acids decomposed more readily with the laccase than did the substituted hydroxybenzoic acids and were transformed to measurable reaction products. A reaction product from HCA was identified astrans-4-hydroxy-3-(trans-4′-cinnamyloxy) cinnamic acid. The possibility of these phenolic acids being polymerized in the tropical peats soils, in particular, is discussed.