We report the formation of poly(methyl methacrylate) (PMMA) microspheres and the coacervation microencapsulation of talc (Mg3Si4O10(OH)(2)) microparticles with PMMA by the pressure-induced phase separation (PIPS) Of CO2-expanded ethanol solutions. PMMA is insoluble in both ethanol and CO2; however, PMMA dissolves in CO2-expanded ethanol and precipitates after the ethanol is depressurized as the solubility of PMMA in CO2-expanded ethanol solutions decreases with the pressure. Coacervation microencapsulation is achieved by mixing a suspension of talc and dissolved PMMA in CO2-expanded ethanol and then depressurizing the system to obtain PMMA microcapsules of talc in a high-pressure cell. The effects of the experimental conditions-depressurization rate, polymer concentration, and evaporation method-on the structure and morphology of the microparticles are investigated by using a scanning electron microscope, a Fourier transform infrared spectroscope, and an electron probe microanalyzer equipped with a wavelength-dispersive X-ray spectroscope. The results reveal that the talc is thoroughly coated with PMMA.