A novel thioxanthone-anthracene (TX-A) photoinitiator, namely 5-thia-pentacene-14-one, possessing the respective photochromic groups was synthesized. TX-A is an efficient photoinitiator for free radical polymerization of acrylic and styrenic type monomers in the presence of oxygen. UV-vis, FT-IR, and fluorescence spectroscopic and polymerization studies revealed that photoinitiation occurs through anthracene chromophore. In contrast to thioxanthone-based photoinitiators, TX-A does not require an additional hydrogen donor for the initiation.