Nucleation and growth of semiconducting ZnO microbelts and nanobelts during thermal evaporation have been investigated. It is found that the ZnO micro- and nanobelts synthesized via thermal evaporation method are mostly nucleated from the attached nanorods and formed by the combination of growth on {(2) over bar 1 1 2} planes and {0 1 (1) over bar 0} planes. The combination of the growth on {(2) over bar 1 1 2} planes is enough for the formation of [0 0 0 1] and [2 (1) over bar (1) over bar 0] oriented nanobelts: but the combination of the growth oil {(2) over bar 1 1 2} and {0 0 1 (1) over bar 0} planes is necessary for the formation of [0 1 (1) over bar 0] oriented nanobelts. In all cases, the growth of ZnO 1D nanostructural materials during thermal evaporation process is accomplished by the packing of ZnO units on different close packed planes. The alteration of growth velocity on different growth direction is the basic reason for the formation of different kinds of ZnO 1D nanostructural materials. (c) 2005 Elsevier B.V. All rights reserved.