CdS nanocrystals with size of 5.0-10.0 nm were synthesized from air-insensitive inorganic precursors of CdCl2.2.5H(2)O and Na2S . 9H(2)O at room temperature in both acidic and basic aqueous solutions under air condition, using the nonionic pluronic amphiphilic triblock copolymer of P123 (H-(-OCH2CH2)(20)[-OCH(CH3)-CH2](70)-(-OCH2CH2)(20)-OH, as well as (EO)(20)-(PO)(70)-(EO)(20)) as the template and structure-directing agent. The X-ray powder diffraction patterns index to the cubic crystal structure of sphalerite for US nanocrystals synthesized. UV-Vis absorption spectra indicate the obvious blue shift for the band gap of Us nanocrystals prepared in the water-rich P123 aqueous solution. (C) 2003 Elsevier B.V. All rights reserved.