Phase behavior studies bf microemulsions containing the monomers methyl methacrylate (MMA), acrylic acid (AA), and tetraethoxysilane (TEOS), the cross-linking agent ethylene glycol dimethacrylate (EGDMA), and water (W), stabilized by the surfactant cetyltrimethylammonium bromide (CTAB), were carried out. An analagous surfactant-free system was also studied and compared with the surfactant-based system. Macroscopically single-phase, transparent microemulsions were formed over a considerable portion of the composition domain for the surfactant-based system. The effects of hydrochloric acid (HCl) and base (NH4OH) on the gel times were examined. Selected compositions in the surfactant-based system were chosen to examine the effect of the water to TEOS ratio (R) on the thermal stability and pore morphology of the polymer composite formed from the hydrolysis and condensation reactions of TEOS and the polymerization of organic-monomer-containing microemulsions. The polymer composites thus obtained exhibit high thermal stability and uniform pore morphology. Thermal stability and pore morphology studies were carried out using differential scanning calorimetry and scanning electron microscopy, respectively. The effect of nitrogen purging on gel time and the effect of EGDMA (a cross-linking agent) on pore morphology are also discussed.