Abstract: In an acetate buffer solution of pH 4.0,a fine polarographic adsorption wave was produced by the complex of Mo(Ⅵ) and calmagite at dropping mercury electrode,with its peak appeared at -0.66 V(vs.SCE).Under optimum condition,linear relationship between the 2nd derivative of peak current (I″p) and the concentration of Mo(Ⅵ) was obtained in the range of 5.0×10-8-1.2×10-5mol·L-1 (r=0.999 7).Detection limit (n=8) of the method was found to be 5.0×10-9mol·L-1 for Mo(Ⅵ).The proposed method has been applied to the determination of molybdenum in some legume samples,giving RSD′s less than 5% and recoveries in the range of 972%-102.0%.The complexing mole ratio between Mo(Ⅵ) and calmagite was found to be 1 to 2.The electrochemical behavior of the polarographic wave was also studied.