Ab initio calculations have been carried out for cycloocta-1, 5- diene-3, 7-diyne at the RHF/6-31G^*^*, RHF/6-31++G^*^*, B3LYP/6- 31G^*^*, B3LYP/6-31++G^*^*, MP2/6-31G^*^* levels. The net charge of each atom and vibration spectra for the optimized geometry have been calculated. The isodesmic reaction and nature bond orbital analyses for cycloocta-1, 5-diene-3, 7-diyne molecule have been obtained at the MP2/6-31G^*^* level. According to the analyses, the results show that cycloocta-1, 5-diene-3, 7-diyne is a rigid planar molecule with relative stability. There is conjugation between C≡C bond and C=C bond. Therefore, the cycloocta-1, 5-diene-3, 7-diyne molecule may have certain aromatic character and stability.

Key words: VIBRATIONAL SPECTRUM, AB INITIO CALCULATION, MOLECULAR STRUCTURE