Abstract: A process for producing a microcellular cast resin product, by casting a water-in-oil emulsion of polymerizable components which will gel and partially polymerize by an exothermic reaction, and placing the partially polymerized casting in a fluid medium maintained at a temperature and pressure such that evaporation of water and monomers is inhibited but sufficient to promote complete polymerization while retaining dispersed water within a microcellular structure. The water content of the emulsion can range from about 1% to about 90% by weight, and the microcellular structure may be either the open cell or the closed cell type.