Cationic polymerization is employed in many commercially important applications, including, for example, decorative and abrasion resistant coatings, printing inks, adhesives, fiber reinforced composites, microelectronic encapsulations, tan coatings, pressure sensitive adhesives, high performance aerospace composites, fiber optic coatings, stereolithography, photoresist and holographic recording media. The term UV cure has also been applied to such processes because the polymerizations are typically induced by light having a wavelength in UV region below about 450 nm. One way to increase cure speed has been to use photosensitizers to increase the photoinitiators response to longer wavelengths. However, many of these compounds are volatile, toxic and potentially toxic. The invention uses novel photosensitizer compositions for increasing the rate of cationic photopolymerization processes with reduced volatility and toxicity.