The ratios of rates constants of hydrogen atom abstraction by a chlorine atom from both sites of asymmetrical chloroethanes were measured in the liquid phase at -13 to 40°C. The following values were obtained: Ethyl chloride (in CC14) 1,l-dichloroethane 1,1,2-trichloroethane The results are compared with recent gas phase data and discussed. Experiments in a complexing solvent (CS,) show an increased selectivity compared to the liquid phase due to both enthalpic and entropic effects. k,,,/kz,r = 10°~21*o.10 exp (86f100/RT) kz,*/k2., = 10°~26*o~10 exp (120f 100/RT) kz,t/kz,s = 10-0.09*0.'0 exp (100f lOO/RT)