A fiberoptic pyrometric technique for the measurement of the temperature of a fuel particle in a fluidized bed reactor is presented. In the fiberoptic pyrometry the thermal radiation emitted by bed and fuel particles is collected and transmitted to a radiometric unit by an optical lightguide immersed into the reactor. The radiation intensity is measured on two narrow wavelength bands and temperatures of the bed and individual fuel particles are determined from these signals. Experimental results obtained in an industrial pressurized fluidized bed gasification pilot plant of 15 MW of thermal power are reported. The temperature of the fluidized bed was 1140-1215 K and the pressure in the reactor was 1.6-2 MPa. A large number of fuel particles both hotter and colder than the surrounding bed were clearly detected. For the hotter particles the temperature elevation with respect to the bed was typically 40-100 K.