The optical characterization and gas sensing properties of Fe3O4 functionalized graphene oxide (GO) composite [Fe3O4-(3-aminopropyl)triethoxysilane GO (APTES-GO)] thin film are discussed in this paper by using spin coating, UV-visible spectroscopy, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction measurements, Surface Plasmon Resonance, and quartz crystal microbalance (QCM) techniques. The Fe3O4-APTES-GO thin films with thickness in the range between 14 and 31 nm have been successfully prepared, when films were spun at speeds between 1000 and 4000 rpm with a refractive index values of between 1.32 and 1.37. In this paper, the swelling behaviors of the Fe3O4-APTES-GO thin films were investigated with respect to volatile organic compounds (VOCs) at room temperature by using the QCM method. The swelling processes could be investigated using the early-time Fick's law of diffusion. Diffusion coefficients were found to be 24.17×10-1 , 13.99×10-16, 3.97×10-16, and 1.73×10-16 cm2 s-1 for dichloromethane, chloroform, benzene, and toluene vapors, respectively. The response of the Fe3O4-APTES-GO films to the these VOCs has been investigated in the conditions of physical properties of the solvents, and the films were obtained to be largely sensitive to dichloromethane and chloroform vapors compared with other studied vapors.