Nanoparticles of ZnO and TiO2 were supported in large quantities on the surface of cotton fibers wrinkled by treatment with supercritical CO2 and water. Nanoparticles of ZnO and TiO2 were deposited onto treated and untreated cotton fibers by an immersion method. The condition of nanoparticles supported on the surface of the fibers was observed by SEM, and the amounts of ZnO and TiO2 supported were quantified by EMPA analysis. The results showed that the cotton fibers treated with supercritical CO2 and water supported far larger quantities of ZnO and TiO2 than the untreated cotton fibers. The amounts of ZnO and TiO2 supported increased with the degree of wrinkling generated on the surface of the treated cotton fibers, and the highest amounts were supported when the fibers were treated with supercritical CO2 and water at (2)0 MPa and 80 degrees C for 1 h. The cotton fibers supporting nanoparticles were tested for the antibacterial e effects of ZnO and whiteness of TiO2. The treated fibers were found to have higher bacteriostatic activity and a higher degree of whiteness than the untreated fibers, and these properties were unaffected by rinsing the fibers in water.