Liquid injections into fluidized beds of solid particles are widely employed in many industrial applications, such as fluid coking, fluid catalytic cracking, and gas-phase polymerization, where rapid and uniform distribution of the liquid feed on fluidized solid particles is of crucial importance for minimizing the formation of undesired agglomerates, and maximizing product yields. Previous studies have shown that the quality of the interaction between liquid jets and a fluidized bed strongly depends upon the injection nozzle technology. To date, however, most of the experimental techniques available for assessing the efficiency of the injection of liquid sprays into a fluid bed are not suitable for scale up. The aim of this work was, thus, to develop at laboratory scale a novel experimental method, which could be easily implemented at larger scales. The signal generated by a triboelectric probe was used to define a performance index for nozzles injecting air-atomized water into a gas-solid fluidized bed. A second performance index was defined, which characterizes the quality of the liquid-solid mixing by means of bed temperature measurements. A linear relationship was found between the two nozzle performance indices. (c) 2007 Elsevier B.V. All rights reserved.