Abstract: A combination reaction chamber and gas/solids separator is provided in a common reactor vessel. The reactor is capable of carrying out various types of gas/solids reactions within the reaction chamber and, contemporaneously, separates the gas from the particulate solids by way of a separator disposed within the reaction chamber. Gas exits the reaction chamber through an outlet disposed along a central axis of the chamber. Solids exit the chamber through an outlet disposed along the outer periphery of the chamber. The reactor provides improved mass transfer rates as well as selective residence times.