High pressure crystallised poly (p-phenylene sulfide) (PPS) samples were investigated with wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The striation appearance, which is the most common feature of polymer extended chain crystals, was clearly observed. Poly (p-phenylene sulfide) extended chain crystals with a C-axis thickness around 10 mu m were formed at high pressure. The DSC results showed that the melting temperature of high pressure crystallised PPS samples was up to 332.3 degrees C, which was higher than the values of ideal PPS perfect crystals used by some researchers, Other morphologies formed at high pressure, including crystalbars and regular polygonal crystals of different characteristics, were also presented with the SEM measurements. The obtained PPS extended chain crystals may be used in the re-evaluation of certain parameters crucial to the processing of PPS products such as the equilibrium melting point and melting enthalpy of ideal crystal.