An integrated interferometric temperature sensor, realized on a silicon substrate, is presented. The device consists of an array of planar Fabry-Pe´rot waveguiding cavities realized by plasma etching and standard microelectronic techniques. Experimental data demonstrating the monitoring of temperature variation both in modulus and sign, with a resolution of approximately I°C, are reported. The influence of the cavity losses and size on the sensor performance is discussed. The realization of amorphous silicon-based guided-wave sensors is then suggested to obtain better temperature resolution.