Potassium iodate KIO₃ single crystal samples have been studied under pressure up to 35 GPa at room temperature. Drastic spectral changes and phase transitions were observed. The first phase transition occurs at 5. 0 GPa characterised by major spectral changes in the Raman bands belonging to the v₁, v₂, and v₄ modes. The other phase transitions were found at 8. 7, 15 and 22 GPa. The v₁ modes soften with pressure up to 15 GPa The phase that is stable between 15-22 GPa has a higher symmetry than the phases in the lower pressures. The IO₃ pyramidal ions may have lost their identity and changed to IO₆ octahedra above 22 GPa, as indicated by the changes in the Raman bands of the v₁ modes and the new bands in the spectral region between 500-600 cm^-1.