A high pressure angle dispersive synchrotron x-ray diffraction study of titanium disulfide (TiS2) was carried out to pressures of 45.5GPa in a diamond-anvil cell. We observed a phase transformation of TiS2 beginning at about 20.7GPa. The structure of the high pressure phase needs further identification. By fitting the pressure-volume data to the third-order Birch-Murnaghan equation of state, the bulk modulus, K0T, was determined to be 45.9 0.7GPa with its pressure derivative, K′ 0T, being 9.5 0.3 at pressures lower than 17.8GPa. It was found that the compression behavior of TiS2 is anisotropic along the different axes. The compression ratio of the c-axis is about nine times larger than the a-axis when pressures are lower than 1GPa. It suddenly decreases to three times larger at pressures of about 3GPa. This ratio shows a linear decrease with a slope of negative 0.048 at pressures below phase transformation.