Mineral nanocrystalline Cu3BiS3 and. Pb1-xBi2/3S (or Bi0.22Pb0.89S1.22) have been prepared at low synthetic temperature of 100-150degreesC by convenient hydrothermal decomposition process. X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectra, and element analysis were used to characterize and measure the samples. The as-prepared Cu3BiS3 sample consisted of whisker-like particles with an average size of 50 x 10 nm(2) and the Pb1-xBi2/3S sample displayed aggregative particles with size in the range of 30-50 nm. Preliminary results showed that the prepared precursors, reaction temperature and time played a role in the formation of the final products. A possible reaction mechanism was also discussed briefly. (C) 2002 Elsevier Science B.V. All rights reserved.