We report on the first direct electrochemistry and fluorescence spectroelectrochemistry of rhodamine 6G at a 4,4'-bipyridine-modified gold electrode. The value of n determined in spectropotentiostatic experiments at 1.87 x 10(-6) mol l(-1) of rhodamine 6G in 0.20 mol l(-1) KCl solution is 1.15, and the experimental value obtained for E-0' is -0.787 V versus Ag \ AgCl \ KClsat, which agrees very well with the value (E-0' = -0.791 V) obtained using cyclic voltammetry at a modified gold electrode. The values of the diffusion coefficients D, and D, for the oxidized and reduced forms of rhodamine 6G calculated from results of potential step and in situ fluorescence measurement experiments are 4.0 x 10(-6) cm(2) s(-1) and 4.2 x 10(-6) cm(2) s(-1), respectively. Cyclic voltammograms of rhodamine 6G show that the peak current I-P is proportional to the square root of the potential scan rate nu (1/2), the ratio of the reduction to the oxidation peak height is about unity, and the separation of both reduction and reoxidation peak potentials DeltaE(P) is essentially constant at 135 mV at low scan rates. These results indicate that electrochemistry of rhodamine 6G at a 4,4'-bipyridine-modified gold electrode is a quasi-reversible one-electron electrode process.