Abstract: A process is presented for the production of high molecular weight polybenzimidazole, in two steps. Step one: provide a first reaction vessel and charge it with at least one aromatic hydrocarbon tetraamine, and a heterocyclic ring making up the dicarboxylic component. Heat the reactants under agitation. Terminate the agitation while continuing to heat the reaction mixture to about 230° C. while allowing the reaction mass to foam. Cool the reaction mass to a friable foamed mass. Crush the friable foamed mass to obtain a ground prepolymer. Step two; provide a second reaction vessel, transferring the ground prepolymer to it. A pressure wash of the first reaction vessel and the means for agitation to obtain a second ground prepolymer. Transfer the second ground prepolymer to the second reaction vessel. Heat the ground prepolymer and second ground prepolymer under agitation to a higher temperature than the first step until the desired degree of polymerization is achieved.