Ounjougou stratigraphic sequence is the most complete record in Western Africa for the Middle Pleistocene. This paper focuses on the lithic industry unearthed in the lowest levels of the sequence. Despite the impossibility to fix the dating of those layers, the assemblage clearly presents Oldowan features. A strong erosive process, combined to the absence of Acheulean industry, strengthens the idea of a probable ancient age for the lithic industry. The technological and techno-functional approach performed to study polyhedrons, spheroids and bolas, abundant in the collection, demonstrates that those artefacts were shaped from independent chaînes opératoires to realize specific tasks. The hypothesis of opportunistic débitage does not fit with these materials at Ounjougou. Flake débitage, retouched flakes and shaped tools on pebbles, along with the polyhedrons, spheroids and bolas component, give the first evidence of an Early Sone Age in stratigraphy in Western Africa.