A bipolar surgical instrument (1) comprises a body (2), first and second opposed jaws (18, 20) located at the distal end of a shaft (10), the first jaw (18) being movable with respect to the second jaw (20) between an open position in which the first and second jaws (18, 20) are spaced apart from one another, and a closed position in which the first and second jaws (18, 20) are adjacent one another. The first and second elongate jaw members (18, 20) have respective first and second electrodes. A power cable having a pair of electrically conductive elements, is provided to connect a source of radio frequency electromagnetic energy to the first and second electrodes. A capacitive element is located in the instrument, and is connected in series between a first one of the pair of electrically conductive elements of the cable and the first electrode.