Vapor pressures and enthalpies of vaporization of the homologous series of n-alkanes CnH2n+2 (20 < n < 38 except n = 29 and 35) have been determined by the torsion-effusion method. Increments of about 2.7 kJ mol-1 of the DELTA(vap)H-degrees(T) for even- and odd-numbered n-alkanes and of about 5.3 kJ mol-1 of the DELTA(sub)H-degrees-298.15 for the even-numbered n-alkanes due to the CH2 increment were found.