Bitumens isolated from the individual soil horizons of the cambisol samples in Boubin-north spruce stand (Sumava Mts.) were analysed using diffuse-reflectance IR spectroscopy (DRIFTS). DRIFTS is suitable as a semiquantitative method for the detection of composition changes of soil bitumens with the increasing soil depth. The aromaticity of soil bitumens decreases, aliphatic chains elongate, and ratio of polar fraction decreases with the increasing depth.