A method of manufacturing a thin film thermistor in which the reagent grade materials are dissolved in water and allowed to intimately mix therein after which the mixture is spray-dried under pressure to obtain a fine powder which is the true thermistor composition desired. After oxidation at high temperatures for a long period of time to remove sulphites etc., the resulting oxides are mixed in a bone milling process with a plastic binder which is then poured on to a glass plate and spread to a predetermined thickness and allowed to dry, after which the material is placed on a ceramic plate and fired to bond the plastic and ceramic and burn out portions of the plastic whereupon electrodes are attached to the final thermistor.