The loss of electrocatalyst activity and electrocatalyst wear are caused by their spontaneous change or by the degradation due to some external processes. The main processes are considered that result in the decrease of the activity of metal, oxidic, carbonaceous catalysts : their corrosion and chemical dissolution, anodic oxidation, cathode deterioration. The increase of temperature, current density, the concentration of ligands and corrosion activators catalysts result in the decrease of the service life. The relation between the service life of the catalysts and these factors is considered. The main methods to increase the service life of catalysts are considered.