The concept of bioreactor is developed since many years in France. To evaluate the humidity distribution in waste mass, sensors and geophysical measurement techniques are needed (Imhoff et al, 2007). The temperature measurement appears as an essential parameter to achieve this goal due to the interpretation facility of the data. Nevertheless, punctual sensor does not offer a global view of the system and the fiber optic sensor seems to be an alternative to cover a large surface (Ettala et al, 2003). The fiber optic sensing technology is known as Distributed Temperature Sensing (DTS). In this study, the use of fiber optic sensor to follow reinjection effects in waste mass was tested. For that, a landfill cell managed on mode bioreactor was implemented with 6 different fiber optic sensors located in a horizontal surface of 20m2 at 3.8m depth from the surface below a leachate recirculation pipe. The temperature variations induced by the leachate diffusion were observed and demonstrated the potential of DTS technology to study the temperature evolution of waste mass in bioreactor.