A polymerizable Norrish Type II photoinitiators includes an optionally substituted benzophenone group or an optionally substituted thioxanthone group exhibiting improved compatibility with and solubility in radiation curable compositions. Radiation curable compositions and inkjet inks can contain these polymerizable Norrish Type II photoinitiators, exhibiting low extractable amounts of the photoinitiators and their residues after curing.
