A process for producing controlled porous epoxy thermosets is presented. It is based on a two-step temperature cure: a polymerization-induced phase separation at a moderate temperature (100120 degreesC) of a thermoplastic, poly(vinyl methyl ether) (PVME), in an epoxy-amine matrix followed by a high-temperature treatment (above 200 degreesC). A porous structure is created by the oxidative thermal degradation of PVME (extraction). Different porous or semiporous structures with submicrometer-sized voids (dispersed closed cells, i.e., spheres or open cells, i.e., bicontinuous percolating canals) are generated depending on the thermoplastic content and the phase-separation mechanism. The morphologies are analyzed quantitatively from transmission electron microscopy (TEM) photographs.