The invention relates to an aqueous colloidal dispersion of a compound of cerium and at least one other element M chosen from among the rare earths other than cerium; titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, aluminium, gallium and zirconium. This dispersion is characterized in that it displays a conductivity of at most 5 mS/cm. It is obtained by a process in which there is reacted with a base a mixture of at least one salt of cerium with at least one salt of an element M mentioned above and in the presence of an acid in a quantity such that the atomic ratio H⁺/(Ce+M) is greater than 0.1, then the precipitate from the preceding reaction is re-dispersed in water. The dispersions of this type cane be used in catalysis, in lubrication, in ceramics, in the manufacture of luminophorous compounds, in cosmetics and as anticorrosion agents.