Vertically well-aligned carbon nanotubes (CNTs) are grown on Fe-deposited silicon oxide substrate at 550 degreesC by thermal chemical vapor deposition of C2H2 gas. We employed two-stage heating technique that the reactants heated at 850 degreesC in the first zone flow into the second zone maintained at 550 degreesC for CNT growth. The CNTs have bamboo structure, closed tip, and defective graphite sheets.