S-1 excited state relaxation processes of [2,2'-bipyridyl]-3,3'-diol are investigated at room temperature in solution. After excitation at 355-360 nm, the transient UV-visible spectra are investigated in the 350-650 nm region where both transient absorption and stimulated emission occur. The signal is measured at various probe wavelengths as a function of time up to delays of 150 ps. The spectral features appear with times shorter than the instrumental resolution (< 200 fs) and evolve with slower dynamics in the 10-20 ps range. A. single-exponential on top of the instantaneous rise of the stimulated emission is observed with time constants of 8-10 ps depending on the solvent. This confirms the coexistence of two proton-transfer mechanisms, one directly forming the di-keto, the other involving the formation of the transient mono-keto tautomer. The transient absorption spectrum intensity decreases following a biexponential law, the fast component coinciding with that of the stimulated emission increase. The slow component is attributed to the decay of the (n, pi*) formed because of its proximity to the (pi, pi*) state.