Abstract: Ultrathin film thermocouple devices, which are extremely small in size and thickness and flexible, allow measurement of temperatures during processing of flexible elements which flex during processing. The invention includes temperature measuring devices where the thermocouple is deposited on the flexible element being processed. Such thermocouple devices are useful in a variety of applications where conventional temperature measuring devices can not be used. Such thermocouples devices are made from a variety of thermocouple metals including copper-constantan and copper-nickel and may be fabricated on flexible substrates by evaporation. Detailed fabrication procedures are also described. These devices are surprisingly robust, able to withstand extensive flexing without alteration or deterioration in thermocouple properties, and exhibit thermal EMF's which are reproducible from sample to sample and readily measurable.