In the production of activated carbon by passing a preheated gaseous activation medium through a zone containing a bed of carbon-containing material while indirectly heating to maintain a temperature of about 500.degree. to 1100.degree. C., supplying carbon-containing material to the bed, and removing activated carbon from the bed, the improvement which comprises introducing the activation medium and the carbon-containing material co-current near the bottom of the zone at a rate such that gaseous products are formed in a quantity sufficient to maintain in the zone a lower static layer and an upper fluidized layer in particular proportions, the rate of supply of the carbon-containing material and withdrawal of activated carbon being related so as to convert about 30 to 55% by weight of the carbon-containing material to gaseous products. The average residence of the carbon-containing material is from about 0.2 to 6, preferably 1 to 4, hours. A suitable apparatus for carrying out the process is described.