Abstract: Apparatus for melting solid particles of synthetic polymer is provided which features an enclosure in which at least one annular member and a heating unit are disposed. The heating unit zigzags in cross-section across the enclosure between the annular member and enclosure inlet. Jacket means substantially surrounds the enclosure at and downstream of a point corresponding to the heating unit. The annular member, heating unit, and jacket means are heated, preferably in series, to above the melt temperature of the solid synthetic polymer particles to provide melting surfaces for the polymer. The molten polymer is withdrawn through an outlet in the base of the enclosure.