Historically, European Lower Palaeolithic cultures have been differentiated according to the presence or absence of bifacial tools. In order to go beyond this typological classification of Homo heidelbergensis groups, we approach the study of their technoeconomic behaviours based on functional and technical analyses. This involves the study of the chaîne opératoire, that is, the entire lithic production process from raw material gathering and tool making to the use, abandonment and/or export out of the site of any artefact. These new data are examined in the light of pluridisciplinary (archaeozoology and palaeoenvironmental) studies. Functional studies on Lower Palaeolithic tools are rare because of the difficulties of working on such ancient materials. Here we present a techno-morphological and functional approach to the analysis of tools and other products of the chaîne opératoire of biface production at Soucy 3P (Yonne, France). The well-preserved archaeological layer at this site is contained in a fluvial sequence within the MIS 9 layer. It has provided faunal remains, as well as a higher quantity of bifaces (n = 276) than usually observed in the Lower Palaeolithic complex of Europe. Despite a quantitatively reduced sample of bifaces and flakes available for use-wear analysis, we have already obtained useful results on lithic technology and tool function. From a technical point of view, the numerous bifaces are bifaces-as-a-tool (pièce bifaciale-outil) according to Boëda (1997). They are very rarely resharpened. When they are, the reduction does not modify their morphological characteristics. Traces resulting from post-depositional phenomena are visible on the artefacts but some use-wear traces can still be seen. The tools show use-wear traces in usually only one active area. Several modes of use have been identified. Although the bifaces may all look the same, their uses varied. Also, the bifaces and flakes may have shared the same modes of use.