Polymer membranes filled with magnetic powder and magnetized, used for an air enrichment, are investigated. Various polymer matrix with different types and granulation of dispersed magnetic powder were used for the preparation of the membranes. All membranes were examined for N-2, O-2, and air permeability. Mass transport coefficients were evaluated basing on Time Lag methods and D1-D8 system. Structure and morphology of the obtained membranes were investigated using fractal analysis. Box counting method for calculating generalized fractal dimension was applied. Obtained results allowed to optimize the preparation procedure of magnetic membranes with the best permeation properties.