Structural properties of energetically low-lying stationary points of the MgSO3 molecular system have been investigated by theoretical density functional techniques. A large number of singlet and triplet structures representing local minima of the neutral MgSO3 molecule are completely characterised. The energetically lowest of these minima is a singlet state of planar kite-shaped C-2v, symmetry. The system equally possesses a variety of stable charged species of which the respectively lowest in energy is presented. We report energies, equilibrium geometric parameters, selected harmonic vibrational wave numbers along with corresponding absorption coefficients. Stability and geometric aspects are compared to the molecules Si2O3 and Mg2O3, as well as to the isoelectronic Al2O3 molecular system. (C) 2002 Elsevier Science B.V. All rights reserved.