Abstract: There are disclosed a process and a plant for gasifying biomass. The plant has a pressure vessel containing a hot fluidized sand bed. The bio-mass is pre-dried to a moisture content of from 10% to 35% by weight. A steam-free oxygen-containing gas is fed and distributed, through a grid system at the bottom of the hot sand bed, to hold the bed in a fluidized state and to form, in its lower portion, an oxygen-rich heat-forming combustion zone and, in its upper portion, a hydrogen-rich gas-forming pyrolysis zone. The pre-dried biomass is uninterruptedly fed in the pyrolysis zone at essentially the center of the hot fluidized bed, this center being determined when the sand bed stands at rest. The fluidized bed is held at an operating temperature of 750.degree. to 860.degree. C. under an operating pressure of 400 kPa to 1750 kPa by controlling the feeding rate of the fluidized gas as well as the feeding rate of the biomass.