Thin films of KCN-etched CuInS 2 surfaces during an annealing procedure are investigated by photoelectron spectroscopy and scanning electron microscopy, combined with energy dispersive X-ray analysis. A significant deviation from stoichiometric composition and the formation of Cu-poor phases after etching is well known. Because of the ternary system the polycrystalline absorber layer need to be characterised in terms of the CuInS 2 monophase, homogeneous elemental distribution or the size of the polycrystalline grains. Here, we present the effect of a heat treatment of samples etched with KCN, a procedure, which leads to surfaces of CuInS 2 with almost ideal elemental composition.