CdS nanocrystals were prepared and further 50 times scale-up syntheses were carried out through a novel ultrasound activation liquid-liquid (water and cyclohexane) two-phase approach at room temperature for the first time. Further preparation of Au/CdS nanocomposites were also realized by the same method. This fast, energy saving, environmentally benign, high-yield approach will benefit greatly to both fundamental mechanism research and industrial utilization development. (c) 2006 Elsevier B.V. All rights reserved.