Thermistor composition

A thick film thermistor composition consisting essentially of admixture of finely divided particles of (a) 5-60% wt. of ruthenium-based pyrochlore;

• (b) 95-40% wt. of a borosilicate glass or mixture of glasses containing by mole %, basis total glass, (1) 65-85% glass-forming oxides containing 25-55% B.sub.2 O.sub.3, 40-10% SiO.sub.2 and 30-0% other glass-forming oxides selected from Al.sub.2 O.sub.3, ZrO.sub.2 and mixtures thereof, and (2) 35-15% glass modifying oxides consisting essentially of 3-35% alkaline earth metal oxide(s) of which no more than about 10% is MgO and 0-28% replacement oxide(s) selected from the group consisting of CuO, Cu.sub.2 O, PbO, ZnO and mixtures thereof, of which none exceeds 10% and the total of which does not exceed 80% of the total glass modifying oxides, the viscosity of the glass upon firing at a peak temperature of 700.degree.-1000.degree. C. being from 10 to 10,000 poises, both of components (a) and (b) being dispersed in (c) an organic medium.