The NMR proton chemical shifts of the CH, group in phenyl phenacyl sulphones (p-keto sulphones) p-X-C6H4S0,CH2COC6H4-Y-p, measured in (CD,), are used t o study transmission of the substituent effect through SO, and CO groups. Contrary to the estimation of this effect from CH,acidities [p(SO,) < p ( C 0 ) l 4 the results were that p(S0,) > p(CO), and it was shown that application of a ; gives a significantly better correlation than that with a,. These findings have been interpreted on the basis of structural data.