The crystal and magnetic structure of the La0.75Ba0.25CoO3 has been studied as a function of temperature and high pressure up to 8 GPa using neutron powder diffraction. The crystal structure of the compound at room temperature is considered to be single phase rhombohedral (space group R3 c), at T = 50 K the crystal structure is described by two-phase model assuming the coexistence of the orthorhombic (Imma) and rhombohedral (R3 c) phases. The magnetic structure is found to be ferromagnetic with Curie temperature about 200 K and magnetic moment 1.6 mu(B) per Co ion. Applied external pressure strongly reduces magnetic moment, it decreases down to 0.7 mu(B)/Co at pressure of 8 GPa. The drop of magnetic moment is associated with a pressure-driven spin state crossover of the cobalt ions from the intermediate spin state to the low spin state. (C) 2016 Elsevier B.V. All rights reserved.