The morphology of syndiotactic polystyrene (s-PS) injection moulded at 50 degrees C and 160 degrees C was examined using polarized optical microscopy, transmission electron microscopy, and Fourier transform infra-red microspectroscopy as a function of mould temperature. A skin/core effect was present and significant structural differences existed at the skin of samples moulded at these two temperatures. Bars moulded at 50 degrees C presented a ’shish kebab’ morphology at the surface while samples moulded at 160 degrees C had ’sheaf’ structures. In the sample moulded at 50 degrees C, crystallinity increased from 19% at the surface to 41% at depths >250 mu m. Such a gradient was not present in the sample moulded at 160 degrees C, which had 46% crystallinity throughout. This crystallinity gradient in samples moulded at 50 degrees C was responsible for the lower chemical resistance of such samples.