Black liquor, a by-product of the papermaking alkaline Kraft process, is an important liquid fuel in the pulp and paper industry. Black liquor consists of Kraft lignin constituents and residual carboxylic acids. The black liquors can be converted to liquid, gas, and char fuels by chemical and thermal treatments. The yields of liquid and gaseous products generally depend on pyrolysis temperature, heating rate, and particle size. The yields of total liquid and gaseous products from the black liquor by pyrolysis increase from 8.5 to 60.2% with increasing temperature from 600 K to 950 K.