Auger electron spectroscopy (AES), electron energy loss spectroscopy (EELS) and factor analysis (FA) have been used to characterize the interface formation during the deposition of nickel on aluminum substrates at room temperature. The analysis of the shape of AES and EELS lines suggests the formation of a Ni-Al compound during the first stages of the deposition. Application of FA to the low-energy Auger electron spectra gives three principal factors that can be attributed to metallic aluminum, metallic nickel and nickel aluminide, respectively. These results, in addition to those on the evolution of the Ni LW versus the Al LW Auger intensity, are consistent with the formation of three monolayers of a Ni,AI compound with an average composition of x = 2, followed by a layer by layer growth of Ni on the NI,AI interface.