In the paper, the distribution of potential energy of gas- phase molecules over the cylindrical pore length is considered. It is shown that, at the pore inlet and outlet, the energy barriers exist which can favor or hinder the gas diffusion into the pore depending on the barrier form. A dependence that allows one to calculate the pore filling by gas-phase molecules with allowance for both geometry and energy parameters of the pore was obtained. The calculations performed showed the possibility of modeling three types of adsorption hysteresis loops included in the classification of the International association of theoretical and applied chemistry.