The effect of reaction temperature of carbon nanotube-confined reaction was discussed by demonstrating the synthesis of Ge nanostructures. The mixture of Ge and GeO2 is used as Ge vapor source. The noticeably different morphology could be observed when the different reaction temperatures were used. Ge quantum dots and their arrangement based on the trace of the starting carbon nanotubes were formed when 1000degreesC of reaction temperature and 1 h of duration time were adopted. The diameter of the quantum dots were found to be strongly depend on the used reaction temperatures and the time:duration. (C) 2002 Elsevier Science B.V. All rights reserved.