Interdiffusion and interface compound formation has been observed at the system Ni/In by using thin‐film couples as well as thin In films on low index Ni single‐crystal substrates. The method applied was the perturbed &ggr;&ggr;‐angular correlation technique, which is very sensitive to local structures and their changes around probe atoms. The successive occurrence of different Ni/In compounds could be observed on isochronal annealing above 230 K. A correlation between the appearance of compounds and In film thickness has been found.