Flue gas purification experiments were performed with a membrane made from the ultrapermeable polymer of intrinsic microporosity (PIM) based on tetramethyltetrahydronaphthalene unit coupled with bicyclic triptycene (PIM-TMN-Trip). Permeation experiments with a CO2-N2-O2-SO2 mixture, simulating flue gas from power plants, were performed by means of an in-house developed permeation unit. The results showed very high permeability of the membrane for sulfur dioxide SO2 and high permeability of CO2, lying mainly between the Robeson upper bound form 2008 and the recently reported upper bound from 2019. Moderately high mixed gas selectivity of SO2 and CO2 with respect to N2 (21-29 and 11-18, respectively), in combination with very high permeability (28∙103 and 30∙103 Barrer, respetively), suggest potential use for industrial gas separation processes. The SO2/CO2 mixed gas selectivity was relatively low (around 1.8), but comparable with other novel membranes, and both are removed simultaneously in the process of CO2 separation.