Abstract: A vending machine for valved cylinders of propane gas is provided which includes a cabinet, a U-shaped roller conveyor and a support rail. The cabinet has return and dispensing openings sized to allow empty cylinders to be returned to the cabinet in an upright orientation and to allow full cylinders to be dispensed from the cabinet in an upright orientation. The return and dispensing openings are vertically offset and horizontally spaced apart. The roller conveyor is within the cabinet and extends from the return opening to the dispensing opening. The roller conveyor is downwardly inclined so that the valved cylinders move along the conveyor by gravity. The support rail extends along both sides of the roller conveyor and maintains the valved cylinders in an upright position while moving from the return opening to the dispensing opening. The vending machine also includes an anti-theft system to prevent unauthorized withdrawals of the valved cylinders from the cabinet.