After synthesis, poly(seleno-p-arylene diamine)s were doped with chlorine. The polymers were studied before and after doping by X-ray photoelectron spectroscopy (X.p.s.), electron spin resonance (e.s.r.) and conductivity measurements. It is suggested that chain ends may be partly terminated by groups containing oxygen. After doping, there is charge transfer complex formation as shown by X.p.s. analysis. In some polymers, the e.s.r. study provided evidence that doping induces carbon radical formation. However, the conductivity remains quite low, whatever the material. This can be explained by small chain lengths and chlorine attack of the chains.