In this report we evaluate the oxidative capacity of native microorganisms from Copahue geothermal system applied to a gold concentrate (71.1 g/t) compared to that showed by some culture collection strains. The sulphide ore, in which gold is present as submicroscopic particles contained in a pyrite matrix, came from several reservoirs of polymetallic ores located in Neuquén, Patagonia Argentina. The ore was processed in Andacollo treatment plant for gold concentration. After biooxidation tests, the highest percentages of solubilised iron were reached in the inoculated system (100% mixed native cultures, 47.8% Leptospirillum ferrooxidans ATCC 29047 and 28.5% for Acidithiobacillus ferrooxidans DSM 11477) while in the sterile control it was only 8.8%. The gold recovery was 96.3% and 45.3% for the treated and untreated concentrate respectively.