The interaction of YBaCuO layers, deposited by atmospheric plasma spraying, with nimonic substrates at high temperature has been studied using X-ray photoelectron spectroscopy and Auger electron spectroscopy (AES). Both the region at the YBaCuO/ nimonic interface and the surface of clean nimonic substrates after annealing in vacuum and oxygen have been studied in terms of chemical composition and peak shapes. Chromium was detected more than 20 ¿m deep in the YBaCuO layer. This is explained in terms of a chemical reaction of Cr3+ oxides from the nimonic with the YBaCuO. Depth profiling of the interface region combined with AES measurements reveals also an extensive migration of nickel oxides from the substrate into the YBaCuO.