Abstract: The invention relates to a control valve for adjusting a process fluid flow of a process plant, comprising a valve housing (8) with a valve seat (14) and a valve member (16) connected to a valve rod (18), which cooperates with the valve seat (14) for opening and closing the control valve (2), wherein the valve rod (18) is electrically connected to the valve housing (8) through a contact device (42, 43, 45). The invention is characterized in that a measuring device (26) for the ohmic transition resistance measurement of the contact device (42, 43, 45) is provided, and that the measuring device (26) is arranged in a measuring line (24) that connects the valve housing (8) to the valve rod (18).