It was found that the real-time fluidization state can be monitored with the help of electric current acquisition during a fluidized bed reduction of iron ore fines, which might be used to the prediction of de-fluidization and localized fluidization state monitoring in a plant-scale fluidized bed. All Fe, FeO, and Fe3O4 phases have been proven to be conductive at high temperatures. In addition, the electric current detected in a fluidized bed under a normal fluidized state is virtually zero even for conductive bed materials. The solid bridges that emerged between these conductive particles were proved to be the cause of conductivity in a fluidized bed. (C) 2018 Elsevier B.V. All rights reserved.