Slurry photocatalyst reactor is difficult to use on large scale and requires additional process to separate the catalyst. Thus, immobilizing photocatalyst titanium dioxide (TiO2) onto support ensures that the material would not be flushed away. In this study, polytetrafluoroethylene (PTFE) membranes� surfaces were modified by grafting with carboxylic acid, wherein TiO2 was subsequently immobilized. High grafting degree of 8.5 was achieved through wet chemistry method using 30 wt acetic acid, at 60 °C via immersion for 2 hours. TiO2 was successfully immobilized onto the membrane (with amount of 11.32 wt), and its presence was confirmed through FESEM-EDX. The leaching test for the first 24 hours shows less than 10 wt was leached out; however, 59 of the TiO2 had leached out after 4 days of the leaching test. Performance test with immobilized TiO2 shows methanol was produced from the photocatalytic CO2 reduction. Additionally, the PTFE-TiO2 membranes exhibit good reusability even after 5 cycles of use. © 2023 The Korean Society of Industrial and Engineering Chemistry