A rough estimate of the bulk organic matter composition in bottom ash was made in this study. This estimate is based on the earlier results of characterisation of aqueous and non-aqueous bottom ash leachates by different analytical techniques, such as TOC measurements, gas chromatography-mass spectrometry, size exclusion chromatography, UV-VIS spectrophotometry, fractionation on XAD resins, and also on other data presented in the literature. These results suggest that cellulose and lignin are the major organic constituents of the bottom ash. Also fractions of water-soluble high-and low-molecular-weight substances as well as a fraction of organics, extractable with non-polar organic solvents were defined. In these extractable aqueous and non-aqueous fractions a number of individual organic substances have been identified.