The invention relates to an electrosurgical device, particularly a surgical instrument having a handle, an elongate shaft protruding from the handle and an end-effector located at the end of the shaft. To allow for rotation of the end-effector, the shaft is connected to a rotation wheel mounted on the handle, towards the rearward end of the handle proximal to the user. The rotation wheel is in the form of a thumbwheel, having an ergonomically designed shape that tapers from a distal direction to a proximal direction, with the angle of the taper matching angle of the outer surface of the handle. The outer tapered surface of the thumbwheel has a number of shaped cut-out or scalloped portions arranged around the outer circumference of the wheel, and arranged in use to receive the tip of a user's thumb to allow the user to rotate the wheel in order to set the rotational orientation of the end-effector. Such an arrangement provides comfortable and easy use of the instrument.