A review concerns characterization of the catalysts based on polymers and compares them with inorganic catalysts. Characterization of microporous polymer catalysts exploited in liquid-phase systems is mainly discussed. Special attention is paid to the combination of methods for the description of mobilities molecules inside the polymer, e.g., to the evaluation of "nanoscopic" morphology from ISEC data, rotational mobility calculated from EPR measurements of a probe confined in the swollen polymer, and self-diffusion coefficients estimated from spin-echo NMR with a steady-state gradient of the superposed magnetic field. The consistency of obtained quantities with the catalytic activity is also discussed.