High transparent and conductive SnO/sub 2/ thin films deposited by spray pyrolysis using SnCl/sub 2/ as precursor solution and HF as source of the doping impurities were characterized through thermoelectric power, Hall voltage and conductivity measurements, in order to determine the influence of the F-content on the electrical transport properties. No doped SnO/sub 2/ samples with high carrier concentrations (about 3/spl times/10/sup 19/ cm/sup -3/) were obtained, possibly as consequence of incorporation of Cl/sup -/ impurities in anion sites of the SnO/sub 2/ lattice during the film deposition. Adding HF to the precursor solution the carrier concentration was increased in about two order of magnitude. It was found that the very low values of resistivity (about 1.7/spl times/10/sup -4/ /spl Omega/cm) presented by the SnO/sub 2/:F thin films are mainly due to a very high concentration of free carriers (about 5/spl times/10/sup 21/ cm/sup -3/) generated by doping at anion sites with Cl/sup -/ and/or F-impurities. The study revealed additionally that the mobility of the free carriers is significantly reduced by increasing of F-concentration, indicating that at room temperature the interaction of free carriers with ionized impurities could be the dominant scattering mechanism.