Experimental data are presented for the rate of stationary two-dimensional nucleation in electrocrystallization of cadmium on the surface of the Cd(0001) crystal face in 2.5 M CdSO4 aqueous solution at 45 degrees C. The overpotential dependence of the nucleus size is determined in a model-independent way, by analyzing the data with the help of the nucleation theorem. The analysis leads to the value of 2.1 x 10(-13) J cm(-1) for the specific peripheral energy of the cadmium nucleus.