This communication gives a detailed characterization of some molybdate solid solutions and cerianite-type material which formed on the French borosilicate nuclear waste glass R7T7 upon corrosion in various saturated salt solutions at 110°C, 150 °C and 190 °C. The glass contained lanthanoid elements, such as neodymium, lanthanum, praseodymium, cerium and yttrium, but did not contain actinoid elements, except uranium and thorium. Various solid solutions containing lanthanoids (Ln) were found on the glass surface after corrosion, including powellite solid solutions and cerianite-type material. The secondary solid phases are characterized based on quantitative microchemical and structural analyses. These phases are expected to incorporate actinoids such as americium and curium in acid magnesiumcontaining salt solutions. The phases then constitute an additional barrier against migration of these radionuclides, which would otherwise be in the aqueous phase.