The reagent 1-(2-quinolylazo)-2,4,5-trihydroxybenzene (QATB) has been used for developing a method for the spectrophotometric determination of nickel (II) and lead (II). Variables influencing the sensitivity of this method such as wavelength, pH and time have been investigated. The limitations of this method and the effect of interfering ions have also been investigated. Few properties of the complexes formed between QATB and metal ions (Ni and Pb) such as composition, stability and free energy of formation have been determined.