Theoretical study of the electronic states of small cationic niobium clusters, Nb n + (n=3-5) Geometries and energy separations of the various low-lying electronic states of Rh 3 ϩ , Rh 4 ϩ , and Rh 5 ϩ clusters with different structural arrangements have been investigated. The complete active space multiconfiguration self-consistent field method, ͑CASMCSCF͒ followed by large scale multireference singles plus doubles configuration interaction ͑MRSDCI͒ computations that included up to 1.6 million configurations for Rh 3 ϩ , 1.5 million configurations for Rh 4 ϩ , and 2.7 million configurations for Rh 5 ϩ , were used. Four nearly degenerate electronic states were found for Rh 3 ϩ . The 6 AЈ electronic state of the pyramidal structure of Rh 4 ϩ was found to be the ground state. Although the 6 AЉ electronic state of Rh 4 ϩ with the same geometry was found to be close in energy at the CASMCSCF level, it is 0.5 eV higher at the higher level of theory. Two nearly degenerate electronic states ͑ 5 AЉ and 5 AЉ͒ of the distorted edge capped tetrahedron structure of Rh 5 ϩ were found as candidates for the ground state of this cluster. Mulliken population analysis has been carried out on these cationic clusters to investigate their bonding properties.