An apparatus for fast pyrolysis of biomass and other solid organic materials including a vertically oriented cylindrical vessel having a solids outlet proximate the bottom thereof, a vapor outlet, a top wall forming at least one opening, and an adjacent heated side wall. Disposed within the cylindrical vessel and extending through the at least one opening in the top wall is a rotor having a rotatable shaft coincident with the longitudinal axis of the cylindrical vessel to which is attached at least one substantially vertically oriented blade having one edge connected directly or indirectly with the rotatable shaft and having an opposite edge spaced apart from the heated side wall, whereby a non-radial, preferably tangential, force is imparted on the feedstock in the cylindrical vessel. Also disclosed is a method for fast pyrolysis of biomass and other solid organic materials.