A gas tank container having increased volume is disclosed. The gas tank container for storing and/or transporting gas and/or liquid, includes a tank vessel, a frame and at least one outlet valve. The end of the outlet valve is attached to a tank flange, which is sunk in a recess at the end of the tank vessel. By recessing at least one outlet valve of the gas tank container, the length of the tank vessel can be optimized within the frame.