A fluidized bed gas distributor is disclosed, wherein the gas distributor allows the fluidized bed to operate with intermittant fluidization, with substantial elimination of natural backflow of fluidized particles. The gas distributor comprises a pair of horizontal pipes disposed within one another, having an annular space thereinbetween. Holes are located in the inner pipe and the outer pipe for the passage of gas therethrough. The holes in the outer pipe are located in the lowermost one-third of the circumference of the pipe and are staggered in a circumferential and/or longitudinal direction relative to the holes in the inner pipe.