The absorption spectra, fluorescence spectra, fluorescence lifetimes, fluorescence quenching, phosphorescence spectra, phosphorescence lifetimes, and picosecond transient absorption spectra of several purinyl-pyridinium salts have been measured in several solvents at room temperature and in ethanol glasses at 77 K. It is concluded that the previously observed photochemical transformation of N-[9-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosyl)purin-6-yl]pyridinium chloride 1 into the highly fluorescent tri-O-acetylluminarosine 6 occurs via an excited triplet state. It is also shown that intersystem crossing in purinyl-pyridinium salts is induced by an intermolecular charge-transfer interaction with the counter ions. Keywords: purinyl-pyridinium salts, fluorescence, phosphorescence.