The potential energy curves of 26 electronic states of 2Σ+g, u, 2Πg, u, and 2Δg, u symmetries of the alkali dimer Na2+, dissociating up to Na(4d) + Na+, are investigated using an ab initio approach involving a nonempirical pseudopotential for the Na+(1s22s22p6) core and core-valence correlation corrections. Furthermore, the transition dipole functions between many electronic states and vibrational energy spacings are presented. The spectroscopic constants of these electronic states are extracted and compared with the available theoretical and experimental results. A very good agreement is observed, especially, for the ground and the first excited states. However, the comparison between our study and the model potential (MP) calculations (Magnier and Masnnou-Seeuws Mol. Phys. 1996, 89, 711) for several states has shown a clear disagreement. The MP well depths of the 3-42Σ+g, 12Πg, 3-42Πg, and 22Πu electronic states are largely underestimated. In addition, the 5-72Σ+g, 3-72Σ+u, 22Πg, 42Πg, and 1-22Δu MP electronic states are repulsive, although in this work, they are attractive with potential well depths of some hundreds of cm−1. The data presented in this study are very useful for studies on ion–atom interaction and cold collision in the presence of electromagnetic fields. © 2013 Wiley Periodicals, Inc.