The protonic conductivity of zirconium phosphate, Zr(HPO4)(2) . H2O(alpha-ZrP), can be increased by dispersion with up to ca. 30 mole% inorganic oxide. This positive composite effect is observed both when alpha-ZrP is coprecipitated from a delaminated form with colloidal silica and when it is intimately dispersed with alpha-Al2O3 by ball-milling. The absolute value of the conductivity depends on the pre-treatment undergone by ZrP but, in all cases, it is enhanced by 5-10 times after composite formation with a maximum observed at ca. 20 mole % inorganic oxide. These effects are explained in terms of local modification of the hydrogen phosphate surface.