The electronic spectrum of the silicon monoxide molecule has been studied theoretically by using ab initiobased multireference singles and doubles configuration interaction calculations, which include the effective core potentials of the atoms. Potential energy curves of all 18 states, which correlate with the lowest dissociation limit Si(P-3(g)) + O(P-3(g)), are constructed. Spectroscopic parameters, namely, T-e, r(e), and omega(e) of a large number of bound A-S states of the molecule, are estimated and compared with the available experimental and other theoretical data. In addition, dissociation energies and dipole moments of the ground and some excited states are computed. The changes in the spectroscopic properties and potential energy curves after the inclusion of the spin-orbit coupling are discussed. Transition probabilities of many dipole-allowed and spin forbidden transitions are reported. The radiative lifetimes of some of the excited states such as A(1)Pi, E(1)Sigma(+), and 2(1)Pi are estimated and compared with the experimental results. Dipole moments (a) and dipole derivatives (partial derivativemu/partial derivativer) of the molecule in X(1)Pi, a(3)Sigma(+), b(3)Pi, A(1)Pi, and E(1)Sigma(+) states as a function of the bond distance have been computed.