Abstract: The invention relates to a method and to a reactor for the single-step polymerization of vinyl monomers by a heterogeneous polymerization in bulk by means of organometalic catalysts. A method according to the invention consists in charging a vertical reactor, which is provided with at least two planetary stirrers situated outside the reactor axis, each stirrer formed from a planar centrally-symmetrical two-blade paddle, with a vinyl monomer, the subsequent introduction of an organometalic catalyst in a solution under stirring and in partial doses amounting to 10.sup.-5 to 10.sup.-3 mole up to the final amount of 5.times.10.sup.-4 to 5.times.10.sup.-2 mole of catalyst per mole of monomer, stirring of the batch, cutting and disintegration of the formed compact mass with the planetary stirrers and its parallel wiping from the surface of reactor with wiping blades until the batch acquires a powdery form and the resulting product is discharged.