Titanium dioxide and polypropylene fibers were prepared by melt-compounding and sputter coating, respectively. Energy dispersive x-ray analysis (EDX) confirmed the presence of titanium dioxide in the fibers. Through the application of environmental scanning electron microscopy (ESEM) and scanning probe microscopy (SPM), it was found that incorporating the titanium dioxide by melt-compounding caused severe aggregation of the titanium dioxide nanoparticles at the polypropylene fiber surface. Indeed, coverage of the fiber surface by titanium dioxide was poor. By contrast, the coverage of the sputter coated fiber surfaces was much more consistent, although aggregation of the titanium dioxide nanoparticles still appeared quite extensive. The behavior of the nanocomposite fiber surfaces was investigated using dynamic contact angle measurements by the Wilhelmy technique. Only a small increase in hydrophilicity of the polypropylene fibers was observed after melt-compounding with titanium dioxide, but a larger increase was noted after sputter coating. UV irradiation appreciably enhanced the hydrophilicity of the fiber surfaces in both cases. © 2007 Springer Science+Business Media, LLC.