Abstract: Thin layers of poly (fluoro aluminium phthalocyanine), (AlPcF)n, are doped by NO2 diluted at various concentrations in N2 and their conductivity variations are studied as a function of time, temperature and doping gas concentration. The doping is reversible. The experimental results are interpreted in terms of adsorption and diffusion of the gas in the polymer, charge transfer and transport of the injected carriers in the polymer. An application of (AlPcF)n thin layers as sensitive part of gas sensor could be considered.