The experimental and theoretical results in neutral aqueous solutions reported here indicate that a proton-coupled electron transfer(PCET)from an alcohol C-H bond to the para-carbonyl is the initial and crucial process for the photoredox reaction of 2-(1-hydroxyethyl)-anthraquinone(HEAQ)to occur while the counterpart 3-(hydroxymethyl)-benzophenone(3-BPOH)compound displays a different PCET from an alcohol O-H bond to the carbonyl as the first step followed by an intersystem crossing process that does not lead to the analogous photoredox,which is caused by a subtle charge-radical coupled effect between HEA Q and 3-BPOH.