A serie of copper field smelting experiments were carried out in order to test assumptions on the copper production processes involved at the Vilabouly Complex, late prehistoric extraction and production site in Central Laos. First analytical results on the Vilabouly Complex assemblage (ores, crucibles, slags fragments and copper alloys objects) along with geological setting information permit to access first hypotheses on the smelting process. The identification of macroscopic layers of matte associated with copper put in light the introduction of sulfidic ores during the process. The presence of this matte in the Vilabouly Complex assemblages raises several questions: to what extend were sulfidic ores used on site? What type of sulfidic ores could have been added? Was it incidental? An unintentional co-smelting seems to be favored dependent on the mineralization exploited that seems mainly to correspond to carbonates/oxidic ores along with a secondary copper sulfide, chalcocite (Cu2S). Therefore, The experimental reconstructions were performed to test this co-smelting of carbonates/oxide along with chalcocite in a one step-process using crucibles as reaction vessels, also based on archaeological observation.