Carbon loss after hydrofluoric acid treatment was between 7% and 23% of initial C and nitrogen loss between 14% and 27% of initial N. The hydrofluoric acid concentration (2% and 10%) influenced the C and N concentration of the HF residue but in most cases not the C and N loss. No change in the isotopic signatures (δ13C and δ15N) were apparent. The bulk chemical composition as seen by 13C CPMAS NMR spectroscopy did not change after HF treatment. (FTIR) spectra of organic horizons were also not affected but analysis of organic matter of mineral rich Oh and Ah horizons became possible only after the treatment. These two methods were not sensitive enough to record changes in OM composition induced by the hydrofluoric acid treatment. Pyrolysis GC/MS showed, in agreement with the wet chemical analysis of non-cellulosic sugars, that some change occurred in the quantity and composition of these saccharides. Lignin analysis suggested that some changes occurred in the composition of the molecule.