Abstract: A coextruded, biaxailly oriented multilayer film comprises a base layer comprising an extremely pure raw material and outer layer. It is suitable for use as an electrically insulating film, as a dielectric in an electrical capacitor, and has improved dielectrical properties for this purpose. The base layer and the outer layer or layers contain propylene polymer on one or both sides and stabilizers for propylene polymers. The raw material for the base layer has an idealized thermal oxidation temperature in the range of 260.degree. to 300.degree. C., preferably in the range 260.degree. to 280.degree. C., and the raw material for the outer layer or layers has an idealized thermal oxidation temperature in the region of 240.degree. to 300.degree. C., preferably in the range 240.degree. to 270.degree. C. The multilayer film as a whole has an idealized thermal oxidation temperature in the range 250.degree. to 290.degree. C., in paticular in the range 250.degree. to 275.degree. C.