A sensitive oscillopolarographic method for the determination of trace boron, based on the complex adsorptive current of the boron-beryllon III system with the anion surfactant sodium dodecyl Sdfak (SDS), which increased the current response about 16 times compared to that obtained without SDS, was reported. Under optimum experimental conditions the limit of detection was 0.5 ng/mI boron. The coordination ratio and the conditional stability constant (K) of the boron-beryllon III complex were estimated to be 1:l and 3.8 X lo", respectively. The existing form of beryllon III and boron-beryllon III at pH 3.7 has been confirmed. The electrochemical behaviour of beryllon III and its complex with boron(M). both in the absence and in the presence of SDS in acetic acid-ammonium acetate (pH 3.7) was investigated. On the surface of a dropping mercury electrode, the adsorption of the B(III)-beryllon III complex in the presence of SDS obeyed the Frumkin adsorption isotherm. The adsorption coefficient ( p = 6.4 X 104), the attraction factor (V = 1.41) and the amount of saturated adsorption ([, = 5.8 X lo-I" mol/cm') were evaluated. The mechanism of the electrode reaction and the enhancement mechanism of SDS have been suggested.