 A novel three-dimensional lead(II) coordination polymer, [Pb3(dmp)2Cl6]n, was prepared by reacting lead(II) chloride with 2,9-dimethyl-1,10-phenanthroline in a fast and facile process. The complex was fully characterized on the basis of its 1H and 13C NMR, IR, and UV spectra and elemental and thermal analyses. The molecular structure of the compound was determined by single-crystal X-ray diffraction and its photoluminescence properties were investigated. The single-crystal X-ray data showed that the compound crystallized in the triclinic crystal system in the space group Pī̄. The complex was utilized as a precursor for the preparation of PbO nanoparticles by direct thermal decomposition at 600 °C in air. The prepared PbO nanoparticles were characterized by scanning electron microscopy and powder X-ray diffraction and a band gap of ca. 3.76 eV was determined from the UV–Vis absorption spectrum. A strong blue emission, centered at 466 nm, was observed in the photoluminescence spectrum of PbO nanoparticles and that related to oxygen vacancies in PbO.