The electrode reaction of (11-ferrocenylundecyl)trimethylammonium bromide (FTMA), a cationic ferrocenyl surfactant, was studied by cyclic voltammetry using a glassy carbon electrode in its aqueous mixtures with sodium dodecylbenzenesulfonate (SDBS), an anionic surfactant. In FTMA-rich mixtures, mixed micelles were formed at low mixing ratios ([SDBS]/[FTMA]), while vesicles (and lamellar liquid crystals) were formed at high mixing ratios except for in the vicinity of the equimolar ratio. Cyclic voltammograms showed that the oxidation peak due to FTMA/SDBS complexes mainly forming vesicles (and lamellar liquid crystals) has an anodic potential which is more positive compared with that due to uncomplexed (free) FTMA molecules forming mixed micelles. At mixing ratios of [SDBS]/[FTMA] less than or equal to 0.30, the oxidation current was caused by the diffusion-controlled process, while at the ratios of 0.40 less than or equal to [SDBS]/ [FTMA] less than or equal to 0.80, the oxidation process was dominated mainly by adsorption species on the glassy carbon electrode because vesicles (and lamellar liquid crystals) deposited onto the hydrophobic carbon electrode due to a high hydrophobicity of vesicle bilayers. In addition, the anodic peak current was strongly affected by the phase behavior of the mixtures. Electrochemical measurements in aqueous solution with a ferrocenyl surfactant would allow us to determine the various aggregation states such as micelles and vesicles.