The isotope exchange technique (IET) was used to measure equilibria and kinetics for adsorption of pure N-2, CH4, and Kr on a 4A zeolite sample. The intracrystalline self-diffusivities for these gases were measured under truly isothermal conditions. The self-diffusivities of Kr and CH4 were smaller than that of N-2 by 2 and 1 order of magnitude, respectively. The self-diffusivity of N-2 was independent of its surface coverage but the self-diffusivities of CIC and Kr increased with increasing coverages in the high-pressure region. This effect was much more pronounced for Kr. The activation energies for self-diffusion of the gases increased in the order Kr > CH4 > N-2 while the isosteric heats of adsorption of these gases in the Henry's law region were very close. The activation energies were larger than the corresponding isosteric heats of adsorption for each gas.