Abstract: Thermostatic control of an electric iron is achieved through utilizing the expansion and contraction of the iron's sole plate relative to a low expansion reference member. In one embodiment, a flexible reference member extends from a fixed mounting at the tip of the sole plate to a switch unit at the rear of the sole plate. The reference number is connected to, and held in tension by, a snap acting actuator within the switch unit, such that as the sole plate expands, the free end of a blade is pulled by the reference member to cause a contact carrying tongue to snap away from a contact to interrupt the power supply. In addition, the temperature of operation may be controlled by varying the effective length of the reference member such as, for example, by deflecting it laterally by a cam member.