Solid solutions of the general formula Ce(1-x)Ln(x)O(2-x/2) square(x/2) (Ln = lanthanide (III) and square = anion vacancy), were prepared by a novel sol-gel route. These materials were characterized by powder diffraction and scanning electron microscopy. The gels formed on sol evaporation were found to be solid solutions with the fluorite structure and a crystallite size of approximately 6 nm. This is the lowest temperature of formation to date. The gels densified readily at 700 degrees C and the lattice parameter of these materials was found to be directly proportional to the ionic radius of the dopant.