Pseudocyclacene structure has been considered for ab initio type calculations (3-21G and 6-31G). The unrestricted Hartree-Fock approach was used throughout the calculations. The pseudocyclacene structure having cyclobutadienic peripheral circuits is estimated to be more stable by 3-21G and 6-31G type calculations. Although, 3-21G type calculations predict discernible stability of transoid form over cisoid form, the 6-31G type cannot differentiate in between these two forms. On the other hand, the total energy calculations at 3-21G and 6-3 1 G levels with MP2 approach point to the biradicalic transoid form to be more stable than the others. (C) 2002 Elsevier Science, B.V. All rights reserved.