It is common practice to store toxic volatile chemicals in a laboratory fume hood. Although this provides safe storage, it becomes necessary to operate the hood continuously, resulting in a continuous loss of conditioned air from the building. Often, bottles containing highly toxic chemicals are few in numbers and small in size so that the storage volume required for this purpose is modest. This makes it possible to utilize a small auxiliary storage cabinet in place of a chemical hood for this purpose, provided all the vapors from the stored chemicals can be retained. We have constructed and tested a passive storage cabinet consisting of a metal box, 30 X 30 X 30 cm, with a front-opening latchable door, a false bottom for catching and retaining liquid spills, and an open top completely covered with a 5-cm depth of tightly packed, gas-adsorbing, activated charcoal. All vapors released inside the cabinet must pass through the charcoal before reaching the outside and are retained on the charcoal. Means are provided to purge the box of residual vapors before opening the door by compressed air line or a hand-operated squeeze bulb. The incoming fresh air sweeps through the chamber and exists through the charcoal filter.