**Abstract**

Black liquor is the wastewater produced from paper-making-pulping industry, which has great threats to the environment and human health. Its pollution handling and resourcing attracted much attention, but conventional method showed several drawbacks, including low energy efficiency, emission of secondary pollutants, and safety and operating issues. Supercritical water gasification (SCWG) is a promising method for organic wastes, especially for those with high moisture content, so it has been widely investigated. A previous study showed that SCWG of pulping wastewater can realize pollution elimination and hydrogen production simultaneously. In this chapter, the recent development of this technology in past decade will be reviewed, including the gasification performance, the influence of the main operating parameter, the catalysts used in this process, the synergetic effect in co-gasification with other energy sources, and the evaluation of integrated system of SCWG of black liquor with pulping process. These progresses have been made will boost the industrial utilization of SCWG of black liquor in pulping industry.

**Keywords:** black liquor, supercritical water gasification, hydrogen, catalysts, co-gasification
