Acidities and bond dissociation energies (BDEs) of the N-H bond in two phenylsulfenylamides, PhSNHBz and PhSNH-t-Bu, and four phenylsulfenylanilides, 4-GC 6 H 4 NHSPh, where G = MeO, H, Br and CN, were measured in order to compare the effects of substituents on acidities and BDEs of N-H bonds with those of C-H bonds. The effects of PhS groups on acidities and BDEs in a series of C-H acids were found to be comparable to those on acidities and BDEs of PhS in a similar series of N-H acids. Comparisons were also made of the effects of changing the oxidation state of sulfur in the series PhS, PhSO and PhSO 2 on the acidities and BDEs of adjacent N-H and C-H bonds in weak acids. Hammett-type plots of pK HA values for phenyl benzyl sulfones (4-GC 6 H 4 CH 2 SO 2 Ph) and phenylsulfenylanilides (4-GC 6 H 4 NHSPh) were linear vs ' p À values. A linear plot was obtained and explained for a plot of BDE of the N-H bonds in remotely substituted phenylsulfonylanilides with ' values. Plots of BDEs vs E ox (A À ) were also linear for 4-substituted phenylsulfenylanilides (4-GC 6 H 4 NHSPh), phenylsulfonylanilides (4-GC 6 H 4 NHSO 2 Ph) and phenyl benzyl sulfones (4-GC 6 H 4 CH 2 SO 2 Ph).