In H2SO4 medium both Nb and Ta form complex with 5-Br-PADAP with maxium absorptions at 605 nm respectively. If the absorbances of the complex mixture and the individual complexes are all measured at both 605 and 506 nm, the contents of Nb and Ta can be calculated easily with an electronic calculator.But the sum of the individual absorbances are not always in good congruity with the absorbance of the complex mixture.By regulation of the concentrations of the reagent and the complexing agent for Nb and Ta and adding alcohol to the solution the absor- bances can be made in good congruity, and linear calibration curves can be obtained.The common elements such as Ti,Fe,Al,Sn, W,Mo,Zr,Mn, Ca, Mg, F-, Cl- etc.do not interfere.