A detailed investigation on the stability and electronic properties of InnNa2 (n = 4-9) clusters is performed by density functional theory, in search for unusually stable motifs. The In6Na2 cluster is characterized by an electronic shell closure with enhanced stability, a larger gap between the highest-occupied and the lowest-unoccupied molecular orbitals, a higher ionization potential, and a lower electronic affinity as compared with adjacent clusters, suggesting that In6Na2 is a magic cluster. Furthermore, the calculated vertical ionization potentials of InnNa2 agree well with available experimental data, indicating that the obtained structures are good candidates for the ground-state geometries of InnNa2. (C) 2013 Published by Elsevier B.V.