Proton-conducting membranes have been obtained by sol-gel synthesis involving tetraethyl orthosilicate and sulfonated suspension copolymers of styrene with allyl glycidyl ether. The membranes are gels consisting of a polymer matrix, in which silica particles are uniformly distributed. The synthesized membranes are characterized by the proton conductivity of up to 4.21 x 10(-2) S/cm at 343 K and 75% humidity, an ion exchange capacity of 3.5 meq/g, a proton-transfer activation energy of 25.2 +/- 2.6 kJ/mol, thermal stability of up to 130 degrees C, and mechanical strength (tensile modulus of elasticity, 322 MPa).