Auger electron spectroscopy and ultraviolet photoelectron spectroscopy were used to study the initial growth and alloy formation of Ni/Pt(1 1 1) ultrathin films. The coverage of Ni calculated by two different theoretical models is comparable to our experimental data. A Pt-rich phase was found on the surface layers by a depth profile after the formation of the Ni-Pt alloy. The UP spectra showed some interesting changes when the coverage of Ni increased and the formation of Ni-Pt alloy occurred. The evolution of the UP peak height can be used to determine the Ni coverage in the initial layer-by-layer growth.