In this study, two different surface modification methods have been tested for easy detection of chloroform, which is harmful to human health in case of excess in the mains water, with a Quartz Crystal Microbalance (QCM) sensor. In the first coating method, acidic and basic solutions of 3-mercaptopropyltrimethoxysilane (MPS) in ethyl alcohol were applied respectively. In the second coating method; Acidic MPS was applied in the first step and then surface modification was completed using 2-mercaptoethanol (ME). In Coating-1, average frequency shifts of -180(±30) Hz, -200(±40) Hz and +40(±10) Hz were recorded for acidic MPS, basic MPS and 10 ng mL chloroform, respectively. In Coating-2, chloroform molecules formed covalent bonds with thiol groups and the mean frequency shifts obtained for acidic MPS, ME and 10 ng / mL chloroform were -180(±30) Hz, -80(±15) Hz, and -70(± 8) Hz, respectively. According to empirical results, coating-2 method provided a better surface modification than coating-1 method. Resonance frequency shifts of -2.5(±1), -12(±4), -70(±8) and -356(±87) Hz respectively were obtained at chloroform concentrations of 0.1, 1, 10, and 100 ng/mL by using QCM sensor modified with MPS + ME.