Abstract In this paper, we conducted an investigation into the use of bubbles modified with cationic surfactants in bubble coalescence inhibition and enhancement of methane-water volumetric mass transfer rate. Various cationic surfactants including hexyltrimethylammonium bromide (HTAB), octyltrimethylammonium bromide (OTAB), dodecyltrimethylammonium bromide (DTAB), and hexadecyltrimethylammonium bromide (HDTAB) were added to aqueous solution and the methane-water volumetric mass transfer coefficient (k L a) values were determined for each of the solutions. Enhancement of methane-water k L a was observed from 14 h −1 to 69 h −1 , depending on the cationic surfactant type and concentration. Enhanced methane-water k L a in aqueous solution by addition of cationic surfactants was employed for the fermentation of methanotroph ( Methylosinus trichosporium OB3b), and cell growth rate and maximum optical density was increased by 391% and 498%, respectively.