The thermal degradation processes which occur in poly(phenylenesulfide) (PPS) have been studied by direct pyrolysis-mass spectrometry (DPMS). The structure of the compounds evolved in the overall temperature range of PPS decomposition (400-700-degrees-C) suggests the occurrence of several thermal decomposition steps. At the onset of the thermal degradation (430-450-degrees-C) this polymer decomposes with the formation of cyclic oligomers, generated by a simple cylization mechanism either initiated at the - SH end groups or by the exchange between the inner sulfur atoms along the polymer chain. At higher temperature (>500-degrees-C) another decomposition reaction takes over with the formation of aromatic linear thiols. The formation of thiodibenzofuran units by a subsequent dehydrogenation reaction occurs in the temperature range of 550-650-degrees-C; in fact, pyrolysis products with a quasi-ladder structure have also been detected. Ultimately, above 600-degrees-C, extrusion of sulfur from the pyrolysis residue occurs with the maximum evolution at the end of decomposition (about 700-degrees-C). It appears, therefore, that the residue obtained at high temperature tends to have a crosslinked, graphite-like structure from which the bonded sulfur is extruded.