Recommended an extraction-spectrophotometric method for determining cupper ions with a solution of 1-(2-hydroxy-1-naphthoiazo)-2-naphthol-4-sulfonic acid. Found optimal conditions: the volume ratio of the organic and aqueous phases is 1:9, the distribution coefficient is 0.95. The light absorption of the complex is 420 nm, the absorption of the reagent is 500 nm, the contrast is 80 nm, this proves the high sensitivity of the developed method. It has been shown that the determination of cupper ions is highly accurate with a lower detection limit of 1.14 μg/L and a correlation coefficient of 0.9999. The developed method for determining cupper ions is applied to the analysis of model mixtures and the relative standard deviation does not exceed 0.0015.