The copolymer of the maleic anhydride-styrene is modified at the presence of 4-amino-2-thiouracil and formaldehyde and the new polymeric sorbate with spatial structure is received. The received sorbate is identified by the IR-spectroscopy method. The complete static sorption capacitance was studied ( K CSSC + = 7.8 mmol/g) and the ionization constants of ionic groups in a sorbate link was defined by electrometric method. Ionization constants were determined by potentiometric titration of the sorbent (