An examination is made of reported experimental and theoretical values of the logarithmic mean excitation energy,l, for the stopping power of molecular hydrogen and of values ofldetermined in this work from various recent experimental values of the stopping cross-section of molecular hydrogen for α-particles and protons of various kinetic energies. Values oflfor molecular hydrogen determined in this work from experimental values of the stopping cross-section reported recently by various investigators give support to a value of over 20 eV forlof molecular hydrogen that was predicted by a recent application of the local plasma model for the determination oflthat took chemical binding into consideration. This value is much higher than all of the previously accepted values oflfor molecular hydrogen.