A series of undoped and potassium-doped catalysts for the oxidative dehydrogenation of propane, based on zirconia-supported V2O5 was investigated by XRD and ESR techniques. The chemical state of the surface and bulk vanadium species and of the ZrO2 matrix was investigated as a function of the calcination temperature and the presence of dopants. It was found that potassium improves the dispersion of surface vanadium species and affects the temperature of the phase transitions of zirconia. These two effects facilitate the incorporation of vanadium (IV) into the ZrO2 matrix. The formation of substitutional solid solution was revealed by Rietveld analysis.