Bidirectional ellipsometry has been developed as a technique for distinguishing among various scattering features near surfaces. The out-of-plane polarized light-scattering by metallic nanoparticles on wafer is calculated and measured. These calculations and measurements yield angular dependence of bidirectional ellipsometric parameters for out-ofplane scattering. The experimental data show good agreement with theoretical predictions for different diameter of gold spheres. The results suggest that improvements for accuracy are possible to perform measurements of scattering features from metallic nanoparticles. The polarization of light scattered by metallic nanoparticles can be used to determine the size of nano-particulate contaminants on silicon wafers.