In this work the feasibility of utilizing hydrogenated amorphous silicon (a-Si:H) films in optical fiber temperature sensors is demonstrated. In this sensor, a-Si:H films are deposited from the glow discharge decomposition of silane gas directly on fiber ends, followed by an aluminum layer obtained by vacuum evaporation. In this manner, the a-Si:H acts like a low-pass filter which cut-off frequency is temperature dependent, modulating the light intensity wich is reflected back into the fiber. This arrangement provides excelent mechanical rigidity and minimum dimensions, limited only by the fiber diameter. Preliminary results, using films deposited at 250°C and a HeNe laser as light source, showed a linear 50% variation in the detected signal, for a 50° C to 200°C temperature variation. In order to obtain similar effects for a 0.8μm LED, thermal annealed films are used.