Cal Sitjo is a new archaeological sequence located in a chert-rich region of the NE Iberian Peninsula, in the town of Sant Martí de Tous (Anoia, Barcelona). The area has undergone significant anthropisation and several archaeological sites (e.g., Vilars de Tous), quarries and workshops for the exploitation of chert (e.g., La Guinardera) have been documented, corresponding to different periods. The abundance of chert made this region an almost obligatory passageway for hunter-gatherer communities such as those occupying the nearby cliffs of Cinglera del Capelló (Capellades), located at a direct distance of 15 km, as well as an ideal settlement for later farming communities. Discovered in 2019, the first excavation campaign was carried out in the fall of 2020. Dates have been obtained from a known sequence of around 8 m, providing a chronological framework that ranges from the Mesolithic to the Middle Neolithic. The preliminary results of this excavation have brought to light lithics, ceramics and charcoals from the Neolithic levels (Levels 3 and 4), and faunal, lithic and charcoal remains from the Mesolithic levels (cleaning section). Our preliminary results confirm that this sequence is an ideal location for a diachronic study of the evolution from the last hunter-gatherers to the first farmers, from a paleoenvironmental and technological perspective, as well as in terms of chert management and distribution in a territory with a great abundance of this raw material.