Investigation of thermally stimulated charge decay (TSCD) and of short-circuit thermally stimulated currents (TSCs) was undertaken in one-sided vacuum aluminized 25 μm thick polystyrene samples subjected to negative corona charging with corona voltages ranging from 6 to 9 kV at temperatures 40°C and above. Charge stability has been found to increase considerably in samples charged above 70°C# This has been considered to be due to the localization of charge carriers in deep traps at higher charging temperatures. These results support the view that the stable electrets suitable for practical use can be obtained by high-temperature corona charging.