Abstract: A method and apparatus for the combustion treatment of a toxic gas which forms microparticles by combustion are disclosed wherein the toxic gas is subjected to a combustion treatment in a specific combustion furnace where the combustion gas formed is brought into contact with an aqueous film flowing downwards on the inner wall of the furnace from the upper end portion thereof to the lower end portion thereof or with a cooled surface, and then optionally with aqueous droplets dispersed in the interior space of the furnace. The water captures the microparticles formed by combustion of the toxic gas and is discharged out of the furnace as a mixed flow with the combustion gas thus treated, and optionally the mixed flow is successively treated in a gas-liquid separator.