This paper describes the construction of the first pressurized black-liquor-gasification test plant in the world and reports experience from its operation. The capacity of the plant is 200 kW based on LHV of the fuel. The high alkaline content in the fuel, about 20% sodium, and the melting point of less than 750°C with high corrosion potential are the major reasons that make black liquor very difficult fuel for pressurized gasification.The low density of the char makes solids circulation difficult in a circulating fluidized-bed gasifier. On the contrary, black liquor is very reactive fuel, three orders of magnitude more reactive than bituminous coals. Laboratory tests related to swelling, pyrolysis, corrosion and reactivity are also described in the paper.