The geometries and vibrational frequencies of C7H22- and C7H32- dianions, as well as their corresponding anions were investigated theoretically using HF, MP2, CCSD and CISD methods.The lowest energy structures are C2C(H2)C42- and C2CHCHCHC22- for C7H22- and C7H32- dianions, respectively.Analysis of possible detachment channels of the two structures indicates that the two isomers are stable with respect to fragmentation into two monoanions.However, the vertical and adiabatic detachment energies of the two structures show that C2C(H2)C42- is electronically stable, while C2CHCHCHC2- is not.