Abstract: A process for producing a polyacetal polymer. The process includes reacting a polyacetal forming polymerization mixture in a polymerization reaction zone, which zone includes an elongated casing substantially following the outer boundaries of at least a pair of shafts, each of the shafts provided with a plurality of intermeshing elliptical shaped plates having flattened edges at the major axis which mesh, wiping the surface of its mating plate. The polymerization mixture is polymerized to form a polyacetal product in the form of a finely divided solid.