Permeation parameters of several organic compounds were determined with a numerical simulation model developed earlier. Diffusivities were determined by calculating permeation curves at various diffusivity values and searching for a value of diffusivity that gave the best correlation of the theoretical curve with the experimental permeation curves. The method also allows determination of error in diffusivity calculation. Error is mainly caused by scattering of experimental data and adding organic interaction with a polymer into the character of a permeation curve. Gas phase distribution ratios were determined from literature data, and permeation selectivities were derived from comparison of experimental data measured by Membrane Inlet Mass Spectrometry (MIMS) and direct inlet measurements. Finding the highest concentration in gas and liquid phase at which the signal still behaves linearly allows estimation of the highest point of linear partitioning. The highest concentration at which diffusivity still remains constant can be estimated by finding the point at which the errors caused by the scattering of the experimental data and the contribution of organic interaction with a polymer into character of a permeation curve are equal. The model was postulated to be applicable over a concentration range in which membrane transport obeys ideal diffusion law, and there is linear sample/membrane partitioning. Calculated membrane diffusivities, water diffusivities, and water/membrane distribution ratios from literature sources were used to simulate permeation fluxes of organic compounds from aqueous phase as a function of the sample flow rate. Comparison of the simulated results showed generally good agreement with the experimental ones, and the expected behavior of permeating flux as a function of sample flow rate was observed.