Many cosmetic products now incorporate sunblock components to protect the skin from harmful ultra violet radiation. These products can be identified by the SPF value quoted on the label. A large proportion of these blocking components are nanoparticles that protect the skin, not by absorbing the harmful radiation, but by scattering it away from the skin. The most commonly used are nanoparticles of zinc oxide and titanium dioxide. This paper will discuss a new method for characterization and quantitation of nanoparticles in sunscreens and cosmetics via the use of UV/Visible spectroscopy. The method utilizes a 150 mm integrating sphere equipped with center mount and is able to quantitate and compare the contributions of absorbance, large particle scattering, and nanoparticle scattering.