Zirconium titanate (ZrTiO4) modified via cerium ions insertion in the oxide lattice has been successfully prepared via Sol-Gel synthesis forming solid solutions in the molar range between 0 and 10%. Cerium ions are hosted both as Ce4+ and Ce3+ ions whose ratio depends on the treatment undergone by the solid, with trivalent cerium always abundantly present even in strong oxidative conditions. Surface exposed Ce3+ ions are capable to adsorb O-2 in the range of temperature between 273 K and 77 K, as superoxide anion (O-2(center dot-)), having side-on structure and characterized by complete surface-to-molecule electron transfer (about 98% of spin density on O-2 molecule). Surprisingly such abundant adsorption is pressure dependent and fully reversible opening the perspective of applications of this system in the field of oxygen separation from gas mixtures.