The cyclic hexamer of p-phenylene sulfide (CHPS) is extracted and isolated from commercial poly(p-phenylene sulfide). The crystal structure change, from the a-form to the P-form, in the CHPS is reported for the first time. Optical microscopy is used to observe the characteristics of the crystals under cross-polarized light. Fourier transform infrared and Raman spectroscopy are used to examine the vibrational characteristics of the crystal as a function of temperature. Scanning electron microscopy is used to examine the shape of the crystals. Differential scanning calorimetry is used to observe the thermal characterization of the sample. Molecular modelling is employed to examine possible conformations. The X-ray powder diffraction pattern is also compared for the two structures. A theory on the crystal structure change is proposed.