A sensitive and selective spectrophotometric method for rapid simultaneous determination of copper and manganese is proposed. The method is based on the ternary metal complexes with alizarin complexone (alizarin-3-methylamine-N,N-diacetic acid , AC) and fluoride, and the use of zero-crossing and derivative ratio spectra techniques. The range 2.54 – 12.7 µg ml^-1 copper could be determined in the presence of 2.19 – 10.9 µg ml^-1 manganese and vice versa. The developed methods were applied for the simultaneous determination of copper and manganese in their binary mixtures and were found to give satisfactory results.