The surface characteristics of materials can be investigated by analyzing their spectral response when properly energized by a suitable source. When the energizing source is represented by a light spectra of known characteristics, the surface response can be evaluated using a spectrophotometric approach. The analysis of the detected spectra can give useful information concerning the material characteristics and/or surface properties and status. This latter aspect is utilized in the present study to set-up a procedure aimed at recognizing particulate solid products belonging to material waste streams. The technique is particularly powerful because its utilization is not linked to the dimension of the image field of the object being investigated. Furthermore the process is flexible since the results of the analysis are influenced by the spectral characteristics of the light source and the acquisition set-up. A great amount of data (one spectra for each investigated element), together with their form (gray tone along a line) represents the analytical challenge to this procedure. In this paper, the above aspects will be analyzed and critically discussed with reference to specific particulate solid waste material sorting.