This work describes the development of porosity in activated carbon honeycomb structures. The honeycombs were fabricated from a combination of synthetic precursors, i.e., phenolic resins, along with several organic and inorganic additives, which allowed their extrusion at room temperature as well as subsequent carbonization and activation. The pore size and pore volume of these structures depend on the level of activation and the precursor composition. It was found that essentially micropores are formed when pure phenolic resin is used. The introduction of metal catalysts in the resin precursor was evaluated as a means to change the pore structure of the final product. The presence of the metal catalyst changes the final pore structure significantly, as evidenced by the formation of a large volume of meso- and macropores, particularly at high activation levels. (C) 2000 Elsevier Science Ltd. All rights reserved.