In this study, the preparation of HCl-doped PEDOT:PSS films was performed on fluorine-doped tin oxide substrates using spin coating method. The only SnO2 peaks were observed in the X-ray diffraction patterns. However, the functional groups that the FT-IR showed match with PEDOT and PSS. Contact angle measurement revealed that contact angle values increased for HCl-doped PEDOT:PSS films in comparison with undoped ones, which implies water tolerance improvement. In terms of optical transmittance, there were similar transmittance spectra for undoped and HCl-doped PEDOT:PSS films. Sheet resistance measurements exhibited that sheet resistance values decreased to the minimum values of 6.67 Ω/sq for HCl-doped PEDOT:PSS conditions. This indicates that the sheet resistance of PEDOT:PSS films can be reduced by HCl. Therefore, the HCl-doping could potentially be a suitable alternative for improving humidity tolerance and conductivity of PEDOT:PSS films.