A novel hybrid photoinitiator, p-benzoyldiphenyliodonium hexafluorophosphate (PhCOPhI(+)PhPF(6)(-)), was synthesized, characterized, and studied. It absorbs UV light not only below 300 nm, but above 300 nm as well. When exposed to UV light, it undergoes an asymmetrical photocleavage to produce cation-radicals and radicals which could induce cationic and radical polymerizations respectively. Compared with the simple iodonium salt PhI(+)PhPF(6)(-), and bimolecular sensitization system PhCOPh/PhI(+)PhPF(6)(-) the covalently bonded photosensitization system PhCOPhI(+)PhPF(6)(-), is much more efficient as a photoinitiator. Oxygen has a small negative effect on the cationic polymerization photoinitiated by PhCOPhI(+)PhPF(6)(-), while isopropanol has a small positive influence only in argon atmosphere.