The electrical capacitance tomography (ECT) with neural network multi-criteria image reconstruction technique (NN-MOIRT) is developed for real time imaging of a gas-solid fluidized bed using FCC particles with evapora- tive liquid injection. Some aspects of the fundamental characteristics of the gas-solid flow with evaporative liquid injection, including real time and time averaged cross-sectional solids concentration distributions, the cross-sectional solids con- centration fluctuations and the quasi-3D flow structures are studied. A two-region model and a direct image calculation are proposed to describe the dynamic behavior in both the bubble/void phase and the emulsion phase based on the tomographic images. Comparisons are made between the fundamental behaviors of the gas-solid flows with and without evaporative liquid injection for various gas velocities ranging from bubbling to turbulent fluidization regimes. Significant differences are observed in the behavior of the gas-solid flow with the evaporative liquid injection compared to the fluid- ized bed without liquid injection. The electrical capacitance tomography (ECT) with neural network multi-criteria image reconstruction technique (NN-MOIRT) is developed for real time imaging of a gas-solid fluidized bed using FCC particles with evapora- tive liquid injection. Some aspects of the fundamental characteristics of the gas-solid flow with evaporative liquid injection, including real time and time averaged cross-sectional solids concentration distributions, the cross-sectional solids con- centration fluctuations and the quasi-3D flow structures are a. direct image calculation are proposed to describe the dynamic behavior in both the bubble / void phase and the emulsion phase based on the tomographic images. Comparisons are made between the fundamental behaviors of the gas-solid flows with and without evaporative liquid injection for various gas velocities ranging from bubbling to turbulent fluidization regimes. Significant differences are observed in the behavior of the gas-solid f low with the evaporative liquid injection compared to the fluid-ized bed without liquid injection.