In this research, nanoparticles and nanostructured thin films of lead sulfide are synthesized by using physicochemical methods at room conditions or suchlike conditions, at short reaction times; furthermore, is used simple laboratory equipment and a simplified experimental configuration. Both syntheses do not employ, ammonium or ammonia to elaborate PbS. The main used precursors for both processes are lead acetate, as the lead source, polyethyleneimine as the complexing agent, and thioacetamide, as the sulfur source. Acetylacetone has been employed as a dispersant agent to elaborate PbS nanoparticles. While the sodium hydroxide maintains a high pH, to elaborate PbS thin films. The characterizations reveal the existence of PbS nanoparticles whose size is smaller than 10nm and with a band gap of 3.35 eV. On the other hand, the resulting thin film is made up of PbS little crystallites of 22 nm in a homogeneous way and its band gap is 1.85 eV.