Abstract: A cabinet, sized to accommodate a compressed gas cylinder, includes a heater which maintains the contents of the cylinder within a desired temperature range. By heating the air surrounding the cylinder, the heater heats not only the cylinder but also its valve and regulator. Vent holes, placed near the top and bottom of the cabinet, provide continuous air flow, preventing possible accumulation of flammable gas in the cabinet in the event of a cylinder leak. The invention is especially useful in maintaining a calibration gas at a temperature which insures the stability of the components of the gas. The invention can also be used in any situation in which it is necessary to heat a compressed gas cylinder.