An inverse algorithm to estimate the adsorption kinetics inside the spherical particles in a constant molarflow (CMF) gas adsorber reservoir by measuring the bulk pressure is developed. The formulation includesKnudsen diffusion, surface diffusion, slip and viscous flows. To obtain an efficient algorithm, the conjugategradient method (CGM) for optimization procedure and the incremental differential quadrature method(IDQM) for solving the governing equations are adopted. The results show that the Knudsen diffusion,surface diffusion, slip and viscous flows effects depend on the type of adsorbate and adsorbent gases. Itis shown that the effective diffusivity is not constant and goes through a minimum at an intermediatepressure. Also, it is found that the Knudsen diffusion and the viscous flow are the dominant parts of themass transfer process at low and high pressure, respectively, and despite the viscous flow, the Knudsendiffusion is highly sensitive to temperature change.