The influence of radioactive krypton85Kr on the surface properties of poly(3-pentylthiophene) has been studied. Irradiation by gaseous85Kr leads to structural polymeric chain changes, which induce after iodine doping the formation of charge-transfer complexes with iodine as well as with gaseous sulfur dioxide manifesting itself by the increased electric conductivity. The presence of ammonia brings about reaction with iodine bound in the complex with a conducting polymer.