In our laboratories we have been studying the synthesis and reactivity of binary actinide and lanthanide intermetallic compounds. In this work, the air-oxidation of ThCu2 and AnNi(2) (An = Th, U) was followed by thermogravimetry (TG) and the products were characterized by X-ray powder diffraction (XRD). The heterobimetallic oxides obtained are described by the formulas 2MO.ThO2 (M = Cu, Ni) and 2NiO.UO3. The thermogravimetric analysis under hydrogen of these heterobimetallic oxides show one mass loss for 2MO-ThO2 and two mass losses for 2NiO'U03 over a wide range of temperature (293-1273 K). The characterization by XRD shows that the reduction products are 2M.ThO2 (M = Cu, Ni) and 2Ni.UO2, with all the actinides in the 4+ oxidation state. The actinide heterobimetallic oxides were described as copper or nickel supported catalysts. (C) 2004 Elsevier B. V. All rights reserved.