The optimum conditions have been established in order to obtain aquaeous extracts of oxidized coal. Coal substrates seem to consist of aromatic polycarboxylic acids and unsaturated aliphatic compounds. Candida tropicalis was adapted to coal extracts, and about 2 g of absolutely dry yeast biomass had been obtained from 600 ml of the substrate in the conditions of a laboratory fermenter. The amino acid composition of the biomass was determined.