Abstract: The redox potential of some cyanine dyes in CH₃OH and CH₃CN was measured using cyclic voltammetry. The unmeasured one was evaluated from the excitation energy by means of the linear correlation analysis. They were compared with the data compiled ’from literature under the same conditions. The effect of many structural factors of cyanine dyes on their redox potential, so on their spectral sensitization was reviewed in detail. A practical approach was suggested to choose excellent sensitizers from the viewpoint of redox potential.