This paper presents early work on Fiber Bragg grating (FBG) as temperature sensor to monitor temperature variation inside a packed-bed non-thermal plasma reactor. FBG made from germania-doped fiber with center Bragg wavelength of 1552.5 nm was embedded inside non-thermal plasma reactor with sphere shape dielectric bead (barium titanate) and used to probe the temperature variation inside the reactor. The experimental works have proven that FBG is a suitable sensor to monitor temperature variation inside of reactor via LabVIEW program. Besides that, Optical Spectrum Analyzer (OSA) recorded Bragg wavelength shift as voltage of power supply increases, which indicate the non-uniform temperature variation occurring inside the reactor. However, it does not affect the chemical reaction inside the reactor because the temperature condition is in steady state.