An oxygen free polycrystalline 6061 aluminum alloy surface was obtained for the first time in an UHV environment (1 x 10(-9) to 3 x 10(-9) Torr) after de ammonia plasma treatment in a separate vacuum system. The specimen was first sputtered and processed in the plasma chamber for about 1 h, transferred after air exposure into the UHV chamber, then cleaned by 2.8 keV Ar+ ion bombardment for about 10 min to remove the air-grown oxide. An oxygen free 6061 aluminum surface was observed using Auger electron spectroscopy. Regrowth of the oxide layer in the UHV environment was monitored versus time. A possible cleaning mechanism by the ammonia plasma is proposed. This oxygen free surface is key to achieving thin film growth/deposition on aluminum or its alloys.