The air-oxidation of the intermetallic compounds LaCu2, CeCu2, PrCu2, and NdCu2 was followed by thermogravimetry. The mass uptake occurred over a wide range of temperature (423-1100 K), leading to two stoichiometries according to the lanthanide : CeCu2O4 and LnCu(2)O(3.5) (Ln La, Pr, Nd). The characterization by powder X-ray diffraction, scanning electron microscopy/energy dispersive X-ray analysis, and surface area measurements showed that segregation took place with the formation of CuO along with CeO2 or Ln(2)CuO(4) (Ln = La, Pr, Nd). Therefore, the oxidized intermetallics are better described by the formulas CeO2 . 2CuO and Ln(2)CuO(4) . 3CuO. The oxidation process noticably increased the surface areas and promoted CuO migration to the surface. These systems exhibited selectivities in 4-methyl-2-pentanol decomposition, which are associated with the lanthanide.