Within thermoelectric generators, the chemical diffusion of a contact material into the active thermoelectric material is a potential cause for degradation, which has rarely been discussed in literature. Frequently, this degradation phenomenon leads to major problems in developing new modules and achieving long-term stability. In this study, copper as one of the standard contact materials and lead telluride as the state-of-the-art active material in the mid-temperature range are investigated. Chemical diffusion experiments of copper in lead telluride were carried out between 375 K and 795 K and the copper diffusion profiles were obtained by Secondary Ion Mass Spectrometry (SIMS). The evaluated chemical diffusion coefficient is lower than 10(-13) cm(2)/s in the respective temperature range. (C) 2017 Elsevier B.V. All rights reserved.