Force fields and vibrational frequencies were calculated for the molecules SOX2 and SeOX2, with X = F, Cl, Br, using DFT techniques. The previously available experimental data and assignments for the six molecules were confirmed by the theoretical results. These data were subsequently used in the definition of the corresponding scaled quantum mechanics (SQM) force fields. A comparison of the obtained internal force constants is made with results reported by other authors for the studied species.Publicado on line 2014.Centro de Química Inorgánica