Cation-conducting hybrid membranes based on poly(vinyl alcohol) modified with furfural, aminosulfonic acid, and tetraethoxysilane have been obtained by the liquid-phase synthesis method in dimethyl sulfoxide. Some of the membranes contain cerium dioxide nanoparticles previously obtained in benzyl alcohol and dispersed in dimethyl sulfoxide using ultrasonic and mechanical homogenizers. The conditions have been determined for obtaining a monodisperse (polydispersity index is 0.08) colloidal CeO2 solution with a particle size of 84 nm. The composition, surface morphology, and physicochemical properties of the obtained materials have been studied. It has been found that the specific ionic conductivity of the hybrid membrane material decreases from 8.4 × 10^–2 to 3.1 × 10^–2 S/cm upon the addition of cerium dioxide, while its oxidative (chemical) stability determined using Fenton’s reagent simulating aggressive operating conditions of a fuel cell increases by 1.5 times. Moreover, in the presence of the metal oxide, the thermal stability and moistureretaining capacity increase, whereas the degree of membrane swelling in water decreases. The operating temperature range of the obtained cation-conducting hybrid materials with and without cerium dioxide is much wider than that of the Nafion reference membrane.