The permeation process of hexane and heptane (nearest homologs) through poly(1-trimethylsilylpropyne) synthesized with catalytic system NbCl5 and TaCl5 was investigated. Dependencies of permeability coefficients on vapor activity were obtained. It was shown that the dependencies are nonlinear, and their character depends on conditions of polymer synthesis, namely which catalytic system used and nature of the vapor/polymer interaction. The influence of film thickness and storage time on dependencies of permeability coefficient on vapor activity was studied as well.