Bi2S3 thin films have been prepared without complexing agent and with different concentrations of ethylene diamine tetra acetic acid (EDTA) as complexing agent by a spray pyrolysis technique. The effect of concentrations of complexing agent on the properties of Bi2S3 thin films is studied by characterizing the films by X-ray diffraction, scanning electron microscopy (SEM), optical absorption and dark electrical resistivity measurement techniques. These studies reveal that all films are polycrystalline. The band gap energy for as deposited films is observed to be 1.72 eV. However, the band gap energy is observed to be 2.0 eV for different concentrations of complexing agent. The electrical resistivity of the films with complexing agent is higher than that of the films prepared without complexing agent. The electrical resistivity also depends upon the concentration of the complexing agent.