Abstract: In an apparatus and process for the activation of carbon from carbon feedstocks by electrical resistance heating in the presence of steam, which comprises preheating particles of the carbon feedstock in a preheater, having the particles descend by gravity into and through a vertical reactor connected to the preheater, introducing steam at the bottom of the reactor so that it moves upward against the downward flow of the particles, passing an electric current through the particles in the reactor, and discharging the activated carbon from the bottom of the reactor, the improvements that comprise feeding the carbon feedstock through the side of the preheater, controlling the electric input, having the reactor project into the preheater, using a knife-gate valve and a discharge-limiting device to control the discharge of the activated carbon, using a carbon feedstock that contains up to about 25% of organic volatiles, maintaining the preheating temperature within a range from about 550.degree. C. to about 750.