Novel nanorods of a lead(II) 3D metal–organic coordination system {[Pb(μ2-NO3)4].(hmta)2.H2O}n (1) (hmta = hexamethylenetetramine) were synthesized by a sonochemical method. The new nanostructure was characterized using scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, elemental analysis, and thermogravimetric analysis. The single-crystal X-ray structure shows that 1 is a three dimensional (3D) coordination compound. This is further self-assembled into a 3-D supramolecular structure by weak directional intermolecular interactions. The coordination number of the Pb(II) ions is eight (PbO8). PbO nanoparticles were obtained by the thermolysis of 1 at 180 °C using oleic acid as a surfactant. The average diameter of the nanoparticles was estimated by the Scherrer equation to be 30 nm. The morphology and size of the prepared PbO samples were also observed using SEM.