A novel nonintrusive technique is presented to investigate hydrodynamic and thermal behavior of gas-solid spout-fluidized beds with liquid injection, by simultaneously capturing visual and infrared images. Experiments were performed in a pseudo-2D bed with draft plates filled with glass or c-alumina particles to investigate the effect of liquid injection and particle properties on the flow characteristics. For the glass particles under dry and wet conditions, time-averaged particle velocities show similar quasi-steady-state behavior. However, under wet conditions, lower particle velocities were observed in both spout and annulus as compared with the dry system. Whereas, c-alumina particles do not show considerable variation in the particle velocities under dry and wet conditions and fluidize well at higher liquid injection rates. Additionally, for the glass particles, the particle temperature significantly decreases as compared to the c-alumina particles. (C) 2015 American Institute of Chemical Engineers