The QCISD(T)/aug-cc-pVQZ and CIS/aug-cc-pVQZ calculations have been carried out to obtain potential energy curves (PECs) of the Cl22- diatomic dianion in order to address possibility of its formation in the merged beam fragmentation of Cl2- questioned based on the observation of the Cl-+Cl+e- channel. Results show that two of the excited states, namely A1Σg and a3Σg are metastable with PECs having wells deep enough to suite several bound states, with minima located at R e =2.8280Å and R e =2.5972Å, and Coulomb barriers of 1648.288 and 1403.835cm −1 heights located at 4.0320 and 3.6130Å, respectively. Transition probabilities and tunneling predissociation lifetimes corresponding to these metastable states are also calculated and analyzed. Ground state X1Σg and excited states B1Σu, C1Πg and D1Πu calculated for this dianion are all repulsive. Calculated Franck–Condon factors suggest that Cl22- can be produced in its excited states via an electron impact process initiating from the ground states of Cl2 and Cl2- .