The electrochemical properties of cobalticenium hexafluorophosphate in water and in oil in water (O/W), dodecane-SDS-n-pentanol-water, microemulsions (ME) are studied through cyclic voltammetry, conductivity, and viscosity measurements at 300 K. The one-electron, reversible redox process of the cobalticenium (CP2CO)(+) reversible arrow cobaltocene (CP2CO)(0) couple exhibit shifts in reaction potential E-1/2 = 1/2(E-pc + E-pa) values, due to the partitioning effect on the probe caused by water soluble CP2CO+ and oil soluble CP2CO species. E-1/2 values shift toward more positive values from its aqueous formal potential -1.086 +/- 0.012 V with the increase in droplet volume fraction (phi(d)) of the ME. Microstructural and dynamic properties of microemulsions, such as droplet diffusion coefficients, surfactant aggregation number, fraction of the free ions, and number density of droplets are evaluated from the electrochemical data. Compositional variations with the electrochemical properties showed O/W droplet to bicontinuous phase transitions at phi(d) = 0.4, which is the percolation threshold. Viscosity and conductivity results also coincide with this value. These results indicate CP2CO+ ion to be a successful electrochemical probe in microemulsions on par with ferrocene.