Analysis for surface chemistry uses electron spectroscopy: AES, XPS and REELS. The excitation and electron emission processes are affected by the competitive surface excitation. Impinging and escaping electrons suffer losses in the solid surface region, producing surface plasmons. The surface excitation is characterized by the surface excitation parameter P-se. A new experimental procedure is described for the determination of P-se. It is based on REELS-EPES, using the elastic peak as reference. The procedure is valid for materials having surface and volume plasmon loss peaks, like Si, In, and Sb. It can be applied for estimating P-se on materials exhibiting a surface loss peak decreasing with energy, like Ag. The ratio of the integrated surface and volume loss peaks is composed and compared with the elastic peak. Experimental results in the E = 0.2-5 keV energy range are presented for several solids.