Abstract: To understand the influences of the acid-base forms of fatty acids on their transfer behavior to mainstream cigarette smoke, pyrolysis and cigarette addition experiments were conducted for eight fatty acids and their corresponding sodium salts. The differences in the pyrolyzates of fatty acids and their sodium salts and the transfer rates to mainstream cigarette smoke were compared, and the effects of tobacco matrix pH on the transfer rates of fatty acids to mainstream cigarette smoke were investigated. The results showed that: 1) The transfer rates of these fatty acids in their original form were higher than 90% under pyrolysis conditions, and the pyrolysis of fatty acid sodium did not produce any fatty acids. 2) The tested fatty acids and the corresponding fatty acid sodium had similar transfer rates (by fatty acids) to mainstream cigarette smoke. 3) The transfer rates of the fatty acids to mainstream cigarette smoke were related to the tobacco matrix's pH, and the tobacco matrix with a lower pH was more conducive to the transfer of the fatty acids to mainstream cigarette smoke.