Abstract: In an ammoniacal buffer medium of pH 8,and in the presence of the surfactant CPC,the reduction of neutral red by hydrogen peroxide was strongly catalyzed by trace amount of cupric ion,leading to an enhancement of the color-fading of neutral red.Linear relationship between values of ΔA (i.e.A0-A) and concentration of Cu(Ⅱ) ion was kept in the range within 120 μg·L-1 as measured at the absorption maximum of 454 nm.Value of detection limit (3S/N) of 2.15×10-8g·L-1 was found for the method.The proposed method was used in the determination of traces of copper in water samples giving results in consistency with the results obtained by AAS.Test for recovery was made by standard addition method,and the values of recovery found were in the range of 97.9%-105.7%.