CL-Out is a consortium of facultative aerobic organisms that are well know for their ability to utilize nitrates. CL-Out is generally used for the aerobic cometabolism of PCE and other chlorinated solvents. As the half-reaction for perchlorate is close to that of nitrate, CL-Out cometabolism of perchlorate was successfully tested in the laboratory. In addition to laboratory tests, CL-Out was applied to field conditions in a pilot study. CL-Out bioremediation successfully reduced the soil perchlorate concentrations by more than 99% and perchlorate concentrations in the downgradient ground water decreased by about 30%.