Grafted copolymer of poly(tetrafluoroethylene ethylene) (ET) with acrylic acid (AAc) was prepared by direct radiation method. The obtained films were modified by treating with small amounts of Co2+ and K+ ions (1.0 wt %). The effects of such treatment on the thermal stability and electrical conductivity of these films were studied. Cobalt treatment did not much affect the thermal degradation of the films. The results obtained revealed that K+ treatment enhanced the thermal degradation of ET-g-PAAc, which started 273 K lower than that observed in the case of the untreated and CO2+-treated films. Potassium and cobalt treatment of the investigated films increased their electrical conductivity (sigma) and decreased the activation energy Delta E-sigma. The increase in sigma values was, however, more pronounced in the case of K+-treated film. These results were discussed in terms of the effective increase in the hydrophilicity of the films, especially those treated with potassium. (c) 2005 Wiley Periodicals, Inc.