Steam activation involves two steps: carbonization and activation at high temperature. Carbonization is done at elevated temperatures in an oxygen-lean environment, which keeps the carbon char from burning.  During high temperature activation, a portion of the carbon atoms in the char are reacted with steam and vaporized as carbon monoxide gas, leaving behind the highly porous carbon structure

Chemical activation is used to produce very high pore volume in wood-based carbons, particularly in the medium-size pore range. The most common process consists of mixing wood dust or some other cellulose-based material with a strong dehydrating agent and then heating to a designated moderate temperature. The activating agent extracts moisture and produces a large internal pore structure as the raw material is carbonized.