Results are presented of large lab. studies on coal desulfurization with foam flotation method improved by application of bioadsorption of Thiobacillus ferrooxidans bacteria to the modifica tion of superficial properties of pyrite particulates from hydrophobic to hydrophillic ones. Results of coal desulfurization with and without bioadsorption have been compared. Bioadsorption improved pyritic sulfur removal by 30% (for coal from ＇Siersza＇ mine; coal size 0.3 to 0.102 mm, S pyritic content 1.69%) after 6-week adaptation of bacteria and 30 min of bioadsorption. Bacteria concentration in 5% water suspension of coal reached 22 mu g of biomass cm(-3).