Rectangular lead selenide and cadmium selenide nanoparticles have been successfully prepared by a photochemical method from an aqueous solution of lead acetate, cadmium chlorate, and sodium selenosulfate in the presence of complexating agents of nitrilotriacetic acid at room temperature. It was found that the effects of the photonic intensity, the pH of the solution, and the species of complexating agents played important roles on the morphology control of the PbSe and CdSe nanoparticles. The products were characterized by X-ray diffraction, electron microscopy, X-ray photoelectron spectra, and photoluminescence spectrum. The mechanism for the formation of the PbSe and CdSe was discussed. (C) 2003 Elsevier Science B.V. All rights reserved.