: In pressure swing adsorption, transmission flow from bed is influenced by the swing pressure until adsorption process is performed in the first half time cycle and in high pressure by adsorbent particles, and the rich output of the desirable component is produced. In the second half time cycle, system pressure is low, and desorption process is done by particles until the bed is dissented from saturation state and is made ready for adsorption process in a new half cycle. This continues in multiple cycles, producing further output. This project addresses the simulation of pressure swing adsorption for the separation of Oxygen from air by means of one packed bed (in adsorption and blow-down stages) and two packed bed (entire Skarstorm cycle: pressurization, adsorption, blow-down and purge stages) using Comsol 4.2a software. Adsorbent particles are of 5A zeolite type. In this simulation, in isothermal state, partial mass balance equations for flow components, along with mid LDF relationship, are solved and Langmuire equilibrium isotherm is employed for the expression of equilibrium concentration of components in intraparticles and interparticles. Under these conditions, based on the changes of flow components’ partial pressure in the direction of bed and time, changes of Molecular and Knudsen diffusion coefficients(diffusion coefficient within the macropores of adsorbent particles) are computed. Also, the effect of employing surface diffusion coefficient (diffusion coefficients within the micropores of adsorbent particles) is investigated. Considering the values of these coefficients and tentative relationships, we obtained the effect of changes of axial diffusion coefficient and effective homogenies diffusion coefficient (in correlation with LDF model) for computing Nitrogen adsorption flux and components’ concentration inter particles. In addition, the effect of changes of flow viscosity, which are due to changes of flow components’ mole fraction in the direction of bed and time, on computing Nitrogen’s adsorption flux and components’ concentration inter particles is examined. The results of this simulation are compared with those of process simulation in isothermal state and in states in which axial diffusion coefficient, effective homogenies diffusion coefficient and flow viscosity are assumed to be independent of position (in the direction of bed) and time. Surface diffusion coefficient is also neglected. The importance of this project lies in more precision computation of Nitrogen’s adsorption flux and components’ concentration inter particles, as compared with previous simulations in isothermal states. Also, in this project, the first half time cycle of Skarstorm cycle is simulated with the combination of orthogonal collocation and Finite volume methods using a computer program. The subject model is the Fick model. Equations employed here include partial mass balance equations for flow components within a bed, partial mass balance equations for flow components within the adsorbent particle, and energy balance equation within bed. In this state, changes of temperatures in the direction of bed and time are considered, but changes of temperatures for adsorbent particles (LiLsx zeolite type) are assumed to be only in the direction of time. Keywords: A process, packed bed, adsorbent particle, micro and macropores, Oxygen, Nitrogen