The silicide formation and the redistribution of Pt after deposition and after a heat treatment at 290 °C of Ni1-xPtxfilms on Si have been analysed by atom probe tomography assisted by femtosecond laser pulses. Two phases with different composition were found to form during deposition at room temperature: a NiSi layer with a relatively constant thickness of approximately 2 nm and a particle of Ni2Si. The shape of the Ni2Si particle is in accordance with nucleation followed by lateral growth formation. After heat treatment, two silicide phases Ni2Si and NiSi were found together with the Ni1-xPtxsolid solution. The redistribution of Pt at the Ni1-xPtx/Ni2Si interface is a clear illustration of the snowplow effect. A segregation of Pt at the Ni2Si/NiSi interface has been observed and is attributed to interfacial segregation. The effect of the redistribution of Pt on the silicide formation is discussed. \textcopyright 2008 Elsevier B.V. All rights reserved.