The mechanism of liquid injection into fluidized bed reactors was investigated by injecting water and ethanol, respectively, into a pilot-scale bubbling fluidized bed (cross section: 1 x 0.5 m) that was kept at temperatures between 120 and 180degreesC. Quartz sand and FCC catalyst were used as bed materials. The injected liquid was found to form agglomerates with the bed particles at the nozzle exit and become transported into the bed interior by mixing of the large-scale solids. There the liquids evaporate from the surface of the particles. (C) 2005 American Institute of Chemical Engineers.