Theoretical investigations were performed to study the structures and properties of different carbon nanoclusters. The computed properties were compared with those of the fullerene. The studied systems included carbon nano capsule, carbon nano bowl (one side closed tube), carbon nano disk and fullerene. The geometries of all species were optimized at the B3LYP level of theory using the 6-31G(d) basis set. Geometry of the silicon analog of fullerene NO was also optimized at the same level of the theory. The HOMOLUMO energy gap, ionization potential and electron affinity of studied clusters are reported and compared with those of the fullerene. It was found that the computed electronic properties are significantly influenced by the shape and size of different carbon nanoclusters. (c) 2006 Elsevier B.V. All rights reserved.