Abstract: A locking shield is provided for covering the fuel cap of particular portable fuel tanks. A tapered flat sheet shield base is structured with a widened end extended, angled, and aperture to be retainably fitted to a fuel tank handle tab adjacent the fuel filler neck. The shield base has flanged sides and is positioned horizontally with the sides and angled end downwardly to cover the fuel filler neck and fuel cap. Extensions of the flanged sides at the narrow end of the shield base are apertured and arranged to position so the device can be padlocked inside the loop of a closed loop handle on the top of the portable fuel tank.