The results of thermal and oxidative stability studies are reported for one perfluorocyclobutane aromatic ether thermoset polymer. The polymer was prepared from 1,1,1-tris(4-trifluorovinyloxyphenyl)ethane by the thermal cyclodimerization of the trifluorovinyl ether functionality, resulting in a network polymer comprising alternating perfluorocyclobutane and aromatic ether groups. The results of isothermal and dynamic thermal gravimetric analysis (TGA) studies are reported with kinetic approximations for decomposition in nitrogen, along with FTIR studies of the oxidative process in air and TGA/mass spec determination of the gasses evolved from decomposition in air. Based on these results, thermal and oxidative decomposition mechanisms are proposed.