In this paper, a new catalytic kinetic spectrophotometric method for the determination of activator aluminum was studied. The method was based on the activation effect of aluminum (III) on the copper (II) which catalyzes the oxidation of pyrocatechol by hydrogen peroxide in acetic acid-sodium acetate buffer solution at pH 5.0. The increase in absorbance of pyrocatechol oxidation product was monitored at 360 nm. The optimization of the operating conditions regarding measuring wavelength, concentrations of the reagents, reaction temperature, reaction time and interfering ions were also investigated and chosen. Under the optimum experimental conditions, the linear range of the determination was 0.0040-0.20 mg.L-1, the detection limit of the method was 8.2 x 10(-7) g.L-1. Combined with separation of extraction of dithizone-carbon tetrachloride solution, the method was applied to the determination of aluminum in water and tea samples with satisfactory results.