The work function changes induced by the adsorption of beryllium on W(211) were measured. It was found that the work function increases steeply in intitial stage of the adsorption reaching a local maximum at the coverage of 1/2 and saturates at approximately 3 monolayers. Starting from 1/2 of the beryllium monolayer an additional peak appears in the spectrum of back-scattered electrons ascribed as due to the excitation of plasma oscillations. Its energy loss of 17.6 eV is distinctly higher than that corresponding to the surface plasmon of bulk beryllium. The explanation of the observed phenomena is proposed.