In modern water treatment practice carboxylic acrylic ion-exchange resins are widely used for partial water softening with simultaneous reduction of its alkalinity. Such cationites have high total exchange capacity (3800 - 4500 mol/m3). They also could be regenerated with stochiometric amount of an acid, including with the acid being in waste solutions, for example, in wastewater of Н-filters of water demineralization plants. At the same time it is known, that at regeneration of carboxylic acrylic cation-exchange resins in the standard water-treatment equipment in one stage with stochiometric amount of a sulfuric acid the 20 - 30 % of total exchange capacity of sorbent is lost unproductively, owing to the high residual contents of desorbed ions in regenerated form of resin. For optimization of a mode of operation of ion-exchange filters with carboxylic acrylic cationites, including due to decrease of a part of ions that have been not desorbed, the approach based on the theory of dynamics of nonequilibrium sorption was developed. It was shown that the simplified dynamics model of one component sorption at intraparticle diffusion in ionite fixed bed describes process of sorbent regeneration adequately irrespective of a way of its organization and allows making a priori estimations of its characteristics changes at variation of linear rate of regeneration solution filtration. It was found a value of effective kinetic coefficient, which knowledge allows to determine all main technical characteristics of regeneration process at a variation of conditions of cationite operation, including realization of two portions scheme regeneration with use of H-filters wastewater of the first stage of water desalination plants.