Arslantepe is a höyük (= tell) located within the fertile Malatya Plain, near the right bank of the Euphrates River. The site is excavated since more than 55 years by the Italian Sapienza University archaeologists and reveals periods from at least the sixth millennium BCE until the final destruction of the Neo-Hittite town. This long sequence records the changing relations and connections with various civilizations and regions of the Near East. Using the chemical characterization of a large group of artefacts (388 analysed), we propose, in this paper, a new sourcing of the obsidian used by the inhabitants of Arslantepe from the beginning of the Late Chalcolithic to the end of the Early Bronze Age. The method is based on the portable XRF analyse of the artefacts and their attribution to a geological source using our database collected within the ongoing " GeObs " project (resp. D. Mouralis) in the Eastern Anatolia as well as previous published data in Central Anatolia and Caucasus. Moreover, the chemical characterization is coupled with the techno-functional determination of the artefacts. The present study conducted by an interdisciplinary research group allows to precise the procurement of obsidian in Arslantepe and to better understand the external relations of the site over time. This research also questions and discusses the preferential choice of the obsidian sources through time, in relation with various factors such as distance, quality and abundance of the raw material as well as socio-cultural influences.