For aesthetic reasons, interest in mould growth on wood for outdoor use in application like claddings has increased during recent years. Products of thermally modified timber are no exception. Thermally modified Scots pine boards have been chemically analysed with regard to their monosaccharide contents. Two industrial thermal modification processes were studied: (1) the ThermoD process in which wood is modified under superheated conditions, and (2) the WTT process in which wood is modified under saturated steam conditions in a closed system. Modified wood samples containing a) only sapwood, b) only heartwood, and c) a mixture of both sapwood and heartwood werechemically analysed with regard to their monosaccharide contents. Different locations (depths) in the cross section of the boards were taken for the analysis. The dried aqueousextract from the modified wood was dissolved in dimethyl sulfoxide, treated withhexamethyldisilazane and trimethylsilyl chloride, and thereafter analysed by gas chromatography (GC-MS). Monosaccharides were identified in the extracts by comparison with the retention times of pure monosaccharides and MS-data. No monosaccharides were found in samples from the ThermoD process, but monosaccharideswere present in samples from the WTT process, the monosaccharide content being dependent on by the location of the sample in the cross-section.