A device (29) for dosed introduction of a fine particle material into a reactor vessel (10) comprising a fluidized bed transfer canal (31) into which a material feeding device (9) opens from the top and into which a gas supply device (33) opens in its lower area, introducing a fluidization gas and presenting an overflow tube (34) to forward the fine particle material. In order to obtain dosed introduction of fine particle material into reactor vessel (10) a plurality of fluidized bed transfer canals (35) are located outside the reactor vessel (10) with overflow tubes (37) protruding inside the reactor vessel (10).