Porous membranes of recycled poly(ethylene terephthalate) (PET) were prepared by nonsolvent-induced phase separation (NIPS) and evaluated for the fi rst time for the fi ltration in high temperature solvents and other harsh environments. The PET was recycled from commercial water bottles. The morphology, pore size, and pore density were optimized by varying the composition of the polymer concentration in the casting solution, the solvent, and the nonsolvent bath in conditions of controlled humidity and temperature. Poly-(ethylene glycol) (PEG) of 0.2 and 1 kg mol−1  was used as an additive and pore inducing agent. The fi ltration performance of the membranes was tested under diff erent solvents and temperatures. The obtained PET membranes were successfully applied for ultrafi ltration with a MWCO of 40 kg mol−1  in dimethylformamide (DMF) at temperatures up to 100° C. PET membranes were found to be resistant to a wide variety of solvents as well as in chlorine and acid medium. They could be used as porous support for thin-fi lm composite membranes and for diff erent applications requiring high chemical and heat resistance.