A simple, rapid, and sensitive single-sweep polarographic method has been developed for investigation of concanavalin A (con A) and its interaction with selected polysaccharides. In a solution containing 0.001 M 2,2'-bipyridine, 0.015 M hexamethylenetetramine, and 0.1 M sodium chloride, con A exhibits a single-sweep polarographic wave, and the cathodic peak potential is -1.50 V (vs SCE). The peak current varies linearly with con A concentration over a range of 1.0 x 10(-8) to 1.2 x 10(-7) M by derivative single sweep polarography. A preliminary discussion on properties of the con A polarographic wave has been made. In addition, it has been demonstrated that single sweep polarography can be a useful method for studies on interactions of con A with its complementary polysaccharides in solution.