The rates of bimolecular elimination from a series of 1-fluoro-2-arylethanes, 1,1-difluoro-2-arylethanes, and 1,1, 1-trifluoro-2-arylethanes have been measured in t-butyl alcohol using potassium t-butoxide as the base. The absolute rate of the reaction and the Hammett rho value for the elimination both increase with the number of fluorines. Values for the latter are +3.24 for the fluoride, +3.56 for the difluoride and +4.04 for the trifluoride, indicating that the transition state is highly carbanionic in character, as is also indicated by a relatively low value of K_H/K_D.