Apparent molar volumes (V-null set) and viscosities of lauric, palmitic, and stearic acids as a function of concentration at (20, 30, 40, and 60) degreesC in 2-butanol are reported. The apparent molar volumes at infinite dilution (V(null set)degrees ) were determined by extrapolating V-null set values to zero concentration. The variations of both V(null set)degrees and viscosity values with temperature and with chain length of fatty acid were examined. V(null set)degrees values were found to decrease with increasing temperature for all three fatty acids and to increase with increasing chain length of fatty acid at a constant temperature. Apparent molar expansivity data at infinite dilution (E(null set)degrees) were derived from the V(null set)degrees versus temperature data determined experimentally. E(null set)degrees values were negative, and their absolute values were found to increase with the chain length of fatty acid. The viscosities do not change appreciably with concentration at constant temperature while they do decrease considerably with temperature at a constant concentration. On the other hand, at a constant temperature and concentration, viscosities increased with increasing chain length.