The light-gated organocatalysis via the release of 4- N , N -dimethylaminopyridine (DMAP) by irradiation of the Ru(bpy) 2 (DMAP) 2 2+ complex with visible light was investigated. As model reaction the acetylation of benzyl alcohols with acetic anhydride was chosen. The pre-catalyst releases one DMAP molecule on irradiation at wavelengths longer than 455 nm. The photochemical process was characterized by steady-state irradiation and ultrafast transient absorption spectroscopy. The latter enabled the observation of the 3MLCT state and the spectral features of the penta-coordinated intermediate Ru(bpy) 2 (DMAP) 2+ . The released DMAP catalyzes the acetylation of a wide range of benzyl alcohols with chemical yields of up to 99%. Control experiments revealed unequivocally that it is the released DMAP which takes the role of the catalyst.