The kinetic and thermodynamic parameters of the decomposition of an inorganic wastewater pollutant such as potassium hexacyanoferrate (III) (PHCF) in the presence of composite catalysts based on polymer track membranes (TeMs) and copper nanoparticles (NPs) was studied. Composite catalysts were prepared by electroless template synthesis using a nontoxic reducing agent - ascorbic acid. A systematic study of the process of electroless plating of copper NPs was carried out depending on pH, deposition time, and the number of activations of the polymer template. The structure of the porous composite catalysts was investigated by scanning electron microscopy and X-ray diffractometry. The catalytic properties of the obtained composites were examined in the temperature range of 10-25 °C for a series of samples synthesized with different deposition times. It was shown that the kinetics of the decomposition reaction of PHCF corresponds to the pseudo first-order reaction. Such thermodynamic characteristics as energy, entropy and enthalpy of activation are calculated. The stability of the properties of catalysts has been studied.