The electronic spectrum of SnSe+ has been studied from the ab initio based multireference configuration interaction calculations which include relativistic effective core potentials of both the atoms. Potential energy curves of all 12 low-lying states, which dissociate into the lowest asymptote Sn+(P-2(u)) + Se(P-3(g)), have been constructed. The ground-state dissociation energy is estimated to be 2.74 eV. Spectroscopic constants of eight low-lying states of SnSe+ within 25000 cm(-1) of energy are computed. The electronic states, which include the spin-orbit coupling, have also been investigated. The ground-state spin-orbit splitting is about 1840 cm(-1). The radiative lifetimes of B(2)Sigma(+), A(2)Sigma(+), and 2(2)Pi states of SnSe+ are calculated. The effect of the spin-orbit coupling on the A(2)Sigma(+)-X(2)Pi transition has been studied in details. The electric dipole moments of the ion in the low-lying states are reported. The vertical ionization energy of the ground-state SnSe is about 8.93 eV. (c) 2005 Elsevier B.V. All rights reserved.