The experience of photo-catalytic and temperature-assisted air and flue gas purification from NOx using pilot- and lab-scale photo-reactors is presented. The reduction of NOx was carried out using real-scale flue gas from coal and natural gas combustion under UV light irradiation (365 nm) over a TiO2 catalyst. The pilot-scale photo-reactor (annular type, diameter of 100 mm and 80 mm, length of 1120 mm, the flow rate of 50-300 L/h of air) was designed and built as a result of our previous project and co-operation. It was proved that moderate temperature (70–120 °C) creates a preferential condition for photo-selective catalytic reduction (photo-SCR) of NOx instead of the existence of the oxidative compound (like O2 and H2O). On the opposite side, the existence of sulfur compounds in flue gas negatively influenced the poisoning of the catalyst surface. As a next step, we propose the application of a pilot-scale photo-reactor to the process of air purification from selected volatile organic compounds (VOCs, like acetone, toluene, formaldehyde, acetaldehyde) and NOx. The experimental setup including a pilot-scale room is presented and discussed. Finally, a new concept of the photo-catalytic reactor for honeycomb shape catalyst is presented and discussed. The challenge of such a type of reactor is sufficient light transporting from the light source to the catalyst surface.