[en] The phase transitions and symmetries in LiKSO₄ are studied by the neutron time-of-flight diffraction. Four from the five transitions given in literature are found in the temperature range of 15 to 960 K. One of the transitions having no ferroelastic nature, is not observed. In three phases the splitting of the diffraction peaks takes place due to domain occurence, confirming thus their ferroelastic nature. The geometry of the splitting gives the symmetry mm2 for the phase appearing for T < 189 K. At the transition into this phase the unit cell deformation consists in a dilation upon orthorhombic axes Δa/a = -Δb/b = 0.018 accompanied by a rotation around the c axis with an angle of 15'. (author)