A new structural phase transition is induced in LiKSO4 crystals by the application of a uniaxial pressure at 77 K. EPR spectra resulting from a MoO43- probe undergo reversible changes as the pressure is increased to about 51 MPa. From a quantitative analysis of the new spectrum above 60 MPa, a space-group change is inferred. These results are corroborated by the evidence of a similar phase transition at 64 K and ambient pressure.