Optical properties of the composite structure a-SiC:H/hemispherical Ag nanoparticles/c-Si were studied using spectroscopic ellipsometry and reflectometry. Hemispherical Ag nanoparticles on c-Si were obtained by chemical deposition from an AgNO₃+HF solution followed by annealing in ambient atmosphere. A layer of a-SiC:H (~50 nm) was deposited on the surface of hemispherical Ag particles using plasma-enhanced chemical vapor deposition. A sharp dip to almost zero was observed in the reflectance spectrum with s-polarization in the wavelength range from 701 to 717 nm, the magnitude of which depended on the angle of incidence of light on the sample. Keywords: hydrogenated amorphous silicon carbide, hemispherical silver nanoparticles, spectroscopic ellipsometry.