Photoreactions of acrylic polymers containing pendant ethyl phenylglyoxylate groups at different distances from the polymeric backbone have been studied. Hydrogen abstraction between pendant groups by an excited triplet phenylglgoxylate carbonyl group from adjacent pendant groups is the primary process. The expected gamma-hydrogen abstraction within one pendant group (the Norrish type II reaction) is not observed. The radicals formed react with each other to form cross-linked structures in the polymer. This effects solubility in various solvents which changes significantly after irradiation. The potential of the polymer as an imageable material has been evaluated.