The photocatalytic degradation of volatile organic compounds (VOCs) from the indoor air is an established method for improving the indoor environment. This paper investigates the photocatalytic degradation of ethyl benzene and toluene by using a new photocatalyst LiNbO3. LiNbO3 is applied as a coating material on the concrete surface and investigate its effectiveness under various operational parameters like the depth of coating, initial concentration of VOCs, etc. The efficiency of VOCs degradation is measured by gas chromatography–flame ionization detector (GC-FID) and scanning electron microscope (SEM) observations. Test results show that the performance of LiNbO3 is better than that of widely used photocatalyst TiO2 in removing VOCs from indoor environment. Degradation rate of VOC increases with the increase of depth of coating. Therefore, LiNbO3 can be used as a promising photocatalyst to remove VOCs from the indoor air.