Methane fermentation, which constitutes at the same time a precious biogas source, is the most frequently applied stabilization method of sewage sludge. Municipal or industrial sewage does not, however, provide for the effective biogas production, mainly on account of their chemical composition. The objective of the paper was to verify susceptibility to the methanation process of the selected organic substrates (refined glycerine, beet molasses, whey) with sewage sludge. The scope of the research covered initial analysis of the raw material (pH, dry mass, dry organic mass), methane fermentation of the suitably prepared samples of fermentation mixtures and the assessment of biogas and methane efficiency. The highest concentration of methane was obtained from the mixture of sewage sludge with refined glycerine (63.10%), whereas the lowest – from the mixture with whey (49.8%).