Abstract: The effect of surfactants on the absorption spectra of 1,5-bis-(2-hydroxy-5-chlorophenyl)-3-cyanoformazan (HCPCF) and l,5-bis-(2-hydroxy-5-sulfo-phenyl)-3-cyanoformazan (HSPCF) and their metallic ion complexes has been investigated. The mechanism of the difference in the interreaction of HCPCFand HSPCFand the corresponding complexes has been interpreted by analysing phenomena concerning electrophoresis and phase separation. For HCPCFand its complexes, the direction of migration under electric field is determined by the charge of the micelle. The presence of Tween-80 has no effect on the migration direction of HSPCFand its complexes, while TPCreverses the migration direction of HSPCFand its metallic complexes. On the basis of these phenomena it has been shown that HCPCFand its complexes can enter into the micellar phase of both cationic and nonionic surfactants, on the other hand HSPCFas well as its complexes can not enter into the micelle of nonionic surfactants. This conclusion has been confirmed by phase separation experiments above the cloud point. The effect of surfactant micelles on the complex formation reaction rate has also been discussed.