The theoretical yield of charcoal from biomass lies in the range 50-80% on a dry weight basis. In spite of the fact that mankind has been manufacturing charcoal for about 6000 years, traditional methods for charcoal production in developing countries realize yields of 20% or less, and modern industrial technology offers yields of only 25-37%. Moreover, reaction times for the batch process in an industrial kiln are typically 8 days. In this article we describe a practical method for manufacturing high-quality charcoal from biomass that realizes near-theoretical yields of 42-62% with a reaction time of about 15 min to 2 h, depending on the moisture content of the feed. Because of its high efficiency, this technology can help to reduce worldwide deforestation and pollution, while providing greater amounts of a desirable, renewable fuel and chemical resource to mankind.