Mostly microporous in nature (with pore diameters less than 2 nm), activated carbons occupy an important position as adsorbent materials and are extensively employed for purification of gases, water and in chemical processing. Conventional activated carbons also contain mesopores (pore diameter in the range 2–50 nm). Application of porous carbon materials as catalytic supports, battery electrodes, capacitors and in biomedical engineering often involves large molecules or macromolecules as adsorbates. For these and similar applications, the carbon materials should possess not only high surface areas, but also high mesopore or macropore (pore diameters above 50 nm) content. Besides contributing to adsorption, mesopores are the main transport arteries for the adsorbate. Typically, mesopore volumes and surface areas of conventional activated carbon are in the ranges 0.1–0.5 cm³/g and 10–200 m²/g, respectively.