We have investigated the influence of the Hubbard (effective) U correction parameter on the structural, local magnetic moment, electronic, mechanical and elastic anisotropy properties of SeXO3 compounds from the first-principles computations. The equilibrium volumes, total energy, bulk moduli and its pressure derivative of the four different magnetic configurations of the SeXO3 compound are assessed by the Murnaghan equation of state fittings. Comparing the ground state of total energy, we have found that the G-type antiferromagnetic configuration in SeXO3 compounds is more stable than other magnetic configurations. Electronic band structure computations indicate that both compounds exhibit a semiconductor behavior. The elastic, polycrystalline elastic and anisotropic properties of both compounds in G-type antiferromagnetic phase were investigated. With the present research, the prediction of these mechanical properties of SeXO3 compounds will guide the elastic constant measurements of these compounds in the future. (C) 2020 Elsevier B.V. All rights reserved.