The samples of polyimide (PI) Upilex(R) were implanted with 10(14) to 10(17) cm(-2) N+ ions at 90 keV and subsequently chlorinated. The UV-visible spectra, Rutherford backscattering (RES) spectra, and sheet resistance were studied on the modified PI samples. The electrical conductivity of the PI samples was found to be an increasing function of the implanted dose. The electrical conductivity of the PI sample implanted with the ion dose of 10(17) cm(-2) is about ten orders of magnitude higher than that of the pristine PI. An additional conductivity increase by a factor two was observed after subsequent chlorination. The enhanced electrical conductivity is related to the production of conjugated double bonds, and, for higher implanted doses, it is also related to the creation of carbonized domains in the sample surface layer. RES analysis shows that the chlorine content in a 150 nm thick surface layer increases, and it reaches a maximum for 10(15) cm(-2) implanted dose. For higher doses, however, the chlorine content declines. The measured concentration depth profile of chlorine incorporated in the sample surface layer was analyzed assuming simultaneous diffusion and chemical reaction.