A fuel cell or battery has an integral multifunction heater element operable as an integral heater, an integral temperature sensor, and/or an integral aid to current collection from the fuel cell. The integral multifunction heater element is embedded within the electrolyte, anode, or cathode, disposed in thermal contact with at least one of the electrolyte, anode, or cathode, and is formed of a thin film of material of suitable resistivity, such as a refractory metal or conductive oxide, patterned in a suitable pattern. Conductive terminals provide electrical contact to the thin film. The integral multifunction heater element may include a thermistor or thermocouple. Methods are disclosed for fabricating and using the fuel cell with an integral multifunction heater element.