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The deposition of PbS thin films by the chemical bath deposition method using sodium citrate as non-toxic complexing agent is presented. As-deposited PbS films and those annealed at 200 and 300 °C in argon atmosphere were formed by tightly compact spherical particles homogeneously distributed along the substrates. The XRD analysis shows that all the films had a galena type cubic crystalline structure. The crystallite size of the as-deposited film was 17 nm which decreased to 14 nm when the film was annealed to 300 °C. Thermal treatments to the films produced a shift of the optical band gap from 1.34 to 1.49 eV. Furthermore, the as-deposited PbS films were photosensitive showing a conductivity of 10-2 Ω-1 cm-1 under illumination. Such a conductivity increased to 10-1 Ω-1 cm-1 with the thermal treatment at 200 °C. The evaluation of the PbS film using a CdS thin film partner as window in the solar cell configuration showed an open circuit voltage of 88 mV and a short current density of 3.5 mA/cm2.