This research article published by IEEE, 2015The properties of Rb 2 I + , RbI 2 - , Rb 3 I 2 + and Rb 2 I 3 - ions were studied using two quantum chemical methods, DFT and Møller-Plesset perturbation theory of the 2 nd order. The effective core potential with Def2-QZVP basis set for rubidium atom and SDB-aug-cc-pVTZ basis set for iodine atom were used. According to the results, the equilibrium geometric structure of the triatomic ions was found to be linear of D ∞h symmetry. For the pentaatomic ions, the three isomeric forms were found: the linear (D ∞h ), the kite-shaped (C 2v ), and the bipyramidal (D 3h ), both for the positive and negative ions. For all species, the equilibrium geometric parameters and vibrational spectra have been determined.