As part of the start up of Los Alamos National Laboratory's new tritium-handling facility, the efficiency of a catalytic oxidation tritium decontamination system was investigated using deuterated methane. The tests were performed during the start up of the facility to confirm the operability of the system before introducing tritium and to provide a baseline for comparison. Techniques and instruments normally used for atmospheric tracer experiments using deuterated methane were applied virtually without modification. The sensitivity of this method allowed preliminary checks at the sub-ppm (v/v) level.