A process for the preparation of high quality char from organic waste materials. The waste is first sorted to remove recyclable inorganic materials of economic value (metals, glass) and other foreign materials that would be detrimental to the quality of the final product (stone, sand, construction debris, etc.). After size reduction, the waste is pyrolyzed at a temperature range of 250 to 600° F., in a high capacity, continuous mixer reactor, using in-situ viscous heating of the waste materials, to produce a highly uniform, granular synthetic product similar in energy content and handling characteristics to, but much cleaner burning than, natural coal.