Diazosulfonates are water soluble, highly photoactive but thermally stable compounds which are prepared from appropriate diazonium salts and sodium sulfite in a diazo coupling reaction. Upon irradiation, the stable trans-isomer is converted into the instable cis-isomer, followed by decomposition via a radical or an ionic mechanism with phenyl radicals or diazonium salts, respectively, as intermediates, depending on the reaction conditions. These chromophores could be incorporated as side groups into polymers via copolymerization, copolycondensation or via polymer analogous reaction. Reaction conditions as well as advantages and disadvantages of these different techniques-and the photochemistry of the polymers are discussed. Diazosulfonate polymers have been applied successfully as photoresins in offset printing techniques. The use in test stripes in quick assays for the detection of phenolic compounds is discussed based on the coupling reaction of the diazonium salt intermediates. In addition, diazosulfonate containing surfactants could be synthesized and were used as photoactive stabilizers in emulsion polymerization and as partners in photoactive polyelectrolyte-surfactant complexes.