The photoreduction of 4,4'-bipyridine (44BPY).by 1,4-dilazabicyclo[2.2.2]octane (DABCO) has been studied in water by picosecond transient absorption spectroscopy and time-resolved resonance Raman spectroscopy. The kinetics of formation of the anion radical 44BPY(-.) by electron transfer have been analyzed and compared with those obtained previously for the same reaction in acetonitrile. The 44BPY(-.) anion is linked via H-bonding to the surrounding water molecules immediately after its formation and undergoes proton transfer along the H-bond to reach an acid-base equilibrium of pK(a) congruent to 15. The nature of the ion pair produced initially in the electron-transfer reaction is discussed.