The results of x-ray photoelectron spectroscopy analysis of a CuNi alloy after a 2 keV Ar+ion bombardment are presented. The spectra, covering the range of 200–1270 eV, include both the data as collected, and after correction for the analyzer response function. Quantification is given after application of the Tougaard background correction both with and without use of reference spectra. The alloy is found to be Cu depleted in the surface region which is consistent with previous works [T. Koshikawa, K. Goto, N. Saeki, R. Shimizu, and E. Sugata, Surf. Sci.79, 461 (1979)].