Abstract: A clamp for mounting a jumper cable to a terminal of a storage battery. The clamp comprises first and second movably mounted jaws having opposed gripping faces which define a gap for receiving the terminal. At least one of the gripping faces has an electrical conductor portion thereon for establishing electrical contact with the terminal. The first jaw has a gear rack mounted thereto, which is engaged by a pinion gear which is rotatably mounted to the second jaw. A worm wheel is mounted coaxially to the pinion gear, and is engaged by a drive worm. A handwheel is provided for manual rotation of the drive worm. The resulting movement of the first jaw relative to the second jaw adjusts the gap so that the battery terminal can be received and gripped therein. The clamp may have a bore which penetrates into the electrical conductor portion of the jaw for receiving an end of the jumper cable in electrical contact therewith, and a setscrew for securing the end of the jumper cable in the bore.