The present invention relates to cerium oxide particles that have excellent heat resistance and/or pore volume especially useful for catalysts, functional ceramics, solid electrolyte for fuel cells, polishing, ultraviolet absorbers and the like, and particularly suitable for use as a catalyst or cocatalyst material, for instance in catalysis for purifying vehicle exhaust gas. The present invention also relates to a method for preparing such cerium oxide particles, and a catalyst, such as for purifying exhaust gas, utilizing these cerium oxide particles.