Relativistic configuration interaction calculations have been carried out to obtain the electronic structure and spectroscopic properties of the low-lying electronic states of SnO+. Potential curves of several A-S states have been generated. Spectroscopic constants of the X(2)Pi, A(2)Sigma(+), and B(2)Sigma(+) states are estimated. The spin-orbit coupling is included in two steps. The computed dissociation energies of the ground and first excited states of SnO+ are compared with the experimental values. The vertical ionization potentials of the ground-state SnO to the ground and first excited states of SnO+ have been calculated. The electric dipole moment functions of the X(2)Pi and A(2)Sigma(+) states of SnO+ are also calculated. The effect of the spin-orbit interaction on the A(2)Sigma(+)-X(2)Pi transition is discussed in detail. The radiative lifetimes of the excited A(2)Sigma(+) and B(2)Sigma(+) states are reported. (C) 2002 Elsevier Science B.V. All rights reserved.