Based on two published UV absorbing molecules 2-(5 0 -tert-butyl-2 0 -hydroxyl)benzotriazole (Tinuvin-PS) and hydroxybenzophenone (HBP), both having characteristic absorption capability, a refined UV absorber, 2-(3 0 -benzoyl-2 0 -hydroxy-5 0 -tert-butylphenyl)benzotriazole, has been synthesized. This new UV absorber exhibits a wider absorption range and better thermal stability compared to either Tinuvin-PS and HBP and a higher absorption efficiency in the UV-C range. Theoretical studies reveal that the UV-C absorption arises from the electron density transfer from the Tinuvin-PS moiety to the HBP moiety and the enhanced absorption efficiency is ascribed to the presence of the carbonyl's π system.