NOVELTY - Preparation of granulated polycrystalline silicon comprises separating a reaction gas containing gaseous silicon compound as silicon metal on silicon particles (which are fluidized to a fluidized bed by fluidization gas) in a fluidized bed reactor with a hot surface, and removing the particles with deposited silicon, unreacted reaction gas and fluidization gas from the reactor.    USE - The granulated polycrystalline silicon is useful for the preparation of electronic devices and solar cells.    ADVANTAGE - The process provides highly pure granulated polycrystalline silicon. The process is economical and consumes less energy.    DETAILED DESCRIPTION - Preparation of granulated polycrystalline silicon comprises separating a reaction gas containing gaseous silicon compound as silicon metal on silicon particles (which are fluidized to a fluidized bed by fluidization gas) in a fluidized bed reactor with a hot surface, and removing the particles with deposited silicon, unreacted reaction gas and fluidization gas from the reactor; where the gas composition contains hydrogen (99.5-95 mol.%) and gaseous silicon compound (0.5-5 mol.%), at the surface of the reactor having a temperature of 700-1400degreesC, which is greater than the temperature of the silicon particle.    An INDEPENDENT CLAIM is included for a fluidized bed reactor, in which the above process takes place comprising a pressure-resistant coat (2), an internal reactor pipe (3) from a material exhibiting high transmission of heat radiation, an inlet (4) for silicon particle, an inlet device (6) for supplying a reaction gas (7), which contains gas or vaporous silicon compound, a gas distribution mechanism for supplying fluidizing gas (9), an outlet (10) for unreacted reaction gas, fluidizing gas and gas or vaporous products of the reaction, which are collected on the fluidized bed surface (19), an outlet (12) for the product, a heating device and a power supply for the heating device and nozzles (18) on the reactor surface, by which the gas composition is supplied into the reactor.    DESCRIPTION OF DRAWING(S) - The diagram shows the schematic representation of the reactor in longitudinal section    Pressure-resistant coat; (2)    Internal reactor pipe; (3)    Inlet; (4)    Inlet device; (6)    Reaction gas; (7)    Fluidizing gas; (9)    Outlet; (10, 12)    Nozzle; (18)    Fluidized bed surface . (19)