At the present time, many publications on mixed matrix membranes (MMM) are concerned with the study of membranes containing nonspherical nanoparticles with high aspect ratios. Macroscopic characteristics of MMMs and their variations are known to be controlled by the parameters of a percolating cluster composed of incorporated particles in the host membrane. However, conditions providing the formation of percolating structures in films, the thickness of which is comparable to the dimensions of incorporated particles, can be appreciably different from the percolation scenario in isotropic infinite systems. In this work, the Monte Carlo method is used to define the conditions providing the formation of a percolating cluster composed of sticks at varying concentrations of sticks in finite membrane and at different ratios between membrane thickness and dimensions of sticks. In the above systems, percolation-induced changes show a threshold character and take place in a narrow concentration interval. Parameters of the as-formed MMMs are found to be unstable and sensitive to both film thickness and aspect ratio of sticks. (C) 2015 Elsevier B.V. All rights reserved