Pyroligneous acid (PA) is a by-product from carbonisation of palm kernel shell (PKS) with more than 200organic compounds, including phenolic and organic acids. The purpose of this study was to characterise andevaluate the effectiveness of PA to protect oil palm trunk (OPT) against fungal attack. Wood vinegar wasproduced at four carbonisation temperatures (i.e., 500°C, 600°C, 700°C and 800°C). The chemical propertiesof PA were measured using Fourier transform infrared (FTIR) spectroscopy and gas chromatography-massspectroscopy (GC-MS). The antifungal assay of PA from carbonisation at 600°C was applied on OPT againsta white-rot fungus, Trametes versicolor, and a brown-rot fungus, Fomitopsis palustris. The effectivenessof PA against both fungi was evaluated by soaking OPT in the PA solution for 24 hr at 25°C, followed byexposure to the media containing the fungi, as stipulated in ASTM D-4455 standard. The lowest meanweight loss (9.33%) was obtained after eight weeks of exposure. The OPT-PA-treated specimen was highlyresistant to the growth of T. versicolor. It was assumed that acid and phenolic components contributed toenhanced growth control of fungi, as indicated from the GC-MS results. The chemical compositions of PAproved that the antifungal activities could be controlled using a high concentration of PA.