During electrodeposition of Sn on Ag substrate an interphase formation /electroimplantation/ could be observed. The average thickness of the formed alloy amounts to 35 nm. Heat treatment increases the thickness of the interphase, the activation energy of the interdiffusion process is 45.5±2 kJ mol–1. The system Sn on Pt substrate showed no electroimplantation. The diffusion during heat treatment has an activation energy of 126.2±2 kJ mol–1. Isomer shift of the formed alloys indicates that Pt diffuses preferentially into the tin layer.