A free-base tetra sodium meso-tetra (p-sulphonatophenyl) porphyrin (TPPS4) and its corresponding metalloporphyrins (MTPPS4), where M = Co, Ni and Zn were synthesized and characterized by UV–visible spectroscopy, infra red spectroscopy and 1H nmr spectroscopy. Thermal studies of these porphyrins were conducted in synthetic air from room temperature to 800 °C. The residues of MTPPS4 were qualitatively analyzed which showed the presence of corresponding metal oxides and Na2SO4. Further, the above porphyrins were subjected to TG-EGA-MS analysis in argon atmosphere to study the evolved gases/species during the thermal events. This information is useful to know the ring opening sequence of these porphyrins at corresponding temperatures.