The room temperature adsorption and temperature-programmed desorption of NO have been performed on unsulfated and sulfated copper zirconia solids(Cu/SZ). Only CuO clusters are present on Cu/ZrO2 and Cu/SZ prepared by the ligand exchange technique with Cu acetylacetonate in organic medium. The sulfation of zirconia induces a stabilization of the mononitrosyl species, adsorbed on Cu, up to approximate to 333 K, and a shift of v(NO) from 1872 to 1910 cm(-1), which shows a decrease of the electron density at the copper sites. Moreover, it inhibits the formation of nitrito or nitrate complexes on copper. This behavior shows the strong interaction between copper and sulfate species and can be viewed either by a dilution phenomenon of the CuO surface by migrating sulfate species or by migration of sulfate anions on the CuO surface.