The glass transition of poly(phenylene sulfide) (PPS) has been examined by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), and energy dispersive X-ray diffraction (EDXD) techniques. All of them evidenced the alpha transition of the polymer, and the results obtained with the different techniques were found to be consistent when the onset point of the DSC trace is taken. The data were analyzed as a function of the rate of heating, and the activation energy of the phenomenon was calculated by assaying the theoretical model of Barton to fit the experimental data.