Normal hemispherical spectral reflectances of plasma sprayed Al 2 O 3 /Al cermets were measured from visible to infrared wavelengths for several metal concentrations ranging from pure alumina to aluminum. Microstructure and composition of the samples were carefully characterized to explain their optical response, highly dependent on volume and/or surface scattering. Besides their contribution to the knowledge of microstructure, 2D scanning electron microscopy and 3D micro-tomography images were exploited to get statistical data in order to generate simplified numerical samples. A Monte Carlo ray-tracing model was then intended to reproduce experimental trends of the optical spectra. A good agreement with the experimental data was obtained.