Natakorn Thamthinawut creator Ekbordin Winijkul Chairperson Thammarat Koottatep Examination Committee Bora, Tanujjal Examination committee Royal Thai Government Fellowship Scholarship Donor text series technical report th Pathum Thani, Thailand Asian Institute of Technology 2021 continuing eng 48 leaves : ill. Nowadays, indoor air quality is a concern of many people since people spend long time indoor than outdoor, and it can cause health problems. Indoor air pollutants are referring to total suspended particles (TSP), Sulfur Dioxide (SO2), Nitrogen Oxides (NOx), and Volatile Organic Compounds (VOCs), etc. Recently, Photocatalyst has been used to remove VOCs for improve indoor air quality. However, the effects of Photocatalyst on the Toluene as total VOCs concentration have not been studied. In this study, the photocatalytic reactor with the size of 22 x 28 x 20 cm3 which was a rectangular box with a volume of 8.5 L was used. An electric fan of 5 V was placed inside the box for completely mix of a Toluene gas in the box. The catalyst plates with the size of 15 x 20 cm2 and a brass valve of 1/4 inches with polyurethane tube of 1/8 inches were used for gas sampling. The measurement of VOC concentration was done by MiniRAE 3000. A Zinc Oxide (ZnO) was coated on glass sheet by hydrothermal synthesis of ZnO nanorods which could provide photocatalytic activity with visible light from halogen lamp source. The catalyst absorption spectrums were peak at 360 nm. The photocatalytic activity test in methylene blue under visible light irradiation demonstrated that there was photocatalytic activity by removing methylene blue by 25% more than photolysis by the removal with only halogen lamp. For the effect of ZnO catalyst with VOC removal, the ZnO catalyst removed 12.57% of VOC at catalyst area per air volume of 37.6 cm2 /L with an irradiation of 450 W/m2 . Increasing in catalyst area increased the VOC removal efficiency. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Environmental Engineering and Management Thesis (M. Eng.) - Asian Institute of Technology, 2021 Zinc oxide Air Pollution Health aspects Volatile organic compounds Environmental aspects Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B13480 http://203.159.5.9/ait-thesis/detail.php?q=B13480 210704 20260817163008.0