TiCl4 forms a molecular structure containing isolated tetrahedral molecules on cooling to 248 K. The freezing pressure of TiCl4 is 0.05 GPa (500 atm). Single crystal growth followed by X-ray diffraction measurements confirm that the phase formed is the same as that obtained on cooling. The Raman spectrum changes abruptly at 1.2 GPa, with the appearance of a bridging mode at 310 cm-1. Synchrotron X-ray powder measurements show that the structure of the high-pressure phase is similar to ZrCl4, the Ti atoms having become 6-coordinate. Long Ti¿Cl contacts in the ambient pressure phase have been converted into primary Ti-Cl bonds by high pressure. We are requesting beamtime to investigate the monomeric to polymeric phase transition by INS on TOSCA, with the aim of measuring the soft mode responsible for the transition.