The polarographic catalytic waves of gallium and indium have bean studied by oscillo-polarogrphy in potassium chloride-sodium acetatealizarin S at pH 5.0. The peak potential appears at -1.13 v (Vs. S. C. E) for gallium and -O.63 v for indium. The wave height is direct1y proportional to the concentration of gallium in the range of 1.5 × 10-7 M to 6 × 10-6 M and indium in range of 4 × 10-6 M to 4×10-6 M. This method has been used for simultaneous determination of trace gallium and indium in ores.