As part of this work the study of transport of organic acids, namely oxalic, tartaric, and lactic acids through polymer inclusion membrane were carried out. As a polymer matrix cellulose triacetate (CTA) and as a carrier 1-alkiloimidazole (IMI-n, n = 10, 11, 12, 14) were used. The aim of this study was to determine the effect of the qualitative and quantitative composition of the polymer inclusion membrane on the transport rate of selected organic acids. On the basis of the obtained results and percolation theory, a theoretical description of the phenomenon of separation processes was proposed. Also, the percolation threshold for the separated organic acids was determined.