As-deposited bismuth sulfide (Bi2S3) thin films prepared by chemical bath deposition technique were treated with thermal annealed in air atmosphere and argon AC plasma. The as-deposited, thermally annealing and plasma treatment Bi2S3 thin films have been characterized by X-ray diffraction (XRD) analysis, atomic force microscopy analysis (AFM), transmission, specular reflectance and electrical measurements. The structural, morphological, optical and electrical properties of the films are compared. The XRD analysis showed that both post-deposition treatments, transform the thin films from amorphous to a crystalline phase. The atomic force microscopy (AFM) measurement showed a reduction of roughness for the films treated in plasma. The energy band gap value of the as-prepared film was E-g = 1.61 eV, while for the film thermally annealed was E-g = 1.60 eV and E-g = 1.56 eV for film treated with Plasma. The electrical conductivity under illumination of the as-prepared films was 3.6 x 10(-5) (Omega cm)(-1), whereas the conductivity value for the thermally annealed films was 2.0 X 10(-3) (Omega cm)(-1) and for the plasma treated films the electrical conductivity increases up to 7.7 x 10(-2) (Omega cm)(-1). (C) 2014 Published by Elsevier B.V.