The reaction of H-atoms with sulfinyl sulfides RS(CH2)(n)SOR' (R, R' = alkyl) in strongly acidic aqueous medium leads, among other reactions, to the reduction of the sulfoxide moiety. This results in the formation of a S.+ radical cation entity which coordinates with the original sulfide moiety to yield the (>S thereforeS<)(+) three-electron-bonded 2/1 sigma* radical cation. The optical properties of this reductively generated species are identical to those for the transients obtained previously upon one-electron oxidation of dithiaalkanes. At sulfinyl sulfide concentrations in the 10(-4)-10(-2) M range the H-.-atom-induced process occurs intramolecularly. The most stable three-electron-bonded radical cation is formed when the two interacting sulfurs are linked via a -(CH2)(3)- chain and a five-membered ring structure can be established. The yields of the (>S thereforeS<)(+)-type transients range from G = 0.2-0.7 (species per 10 J absorbed energy) with the high value pertaining to the reduction of MeS(CH3)(3)SOMe (0.01 M) in aqueous, N-2-purged, 3 M HClO4 solutions. These yields are significantly below the yield of H--atoms, indicating competing processes such as H-atom abstraction and reaction of H-. with 2-methyl-2-propanol (which was added for removal of (OH)-O-. radicals). The rate constant estimate of (1.8 +/- 0.2) x 10(7) M-1 s(-1) for the reaction of H-. + MeS(CH2)(3)SOMe appears to be typical with respect to the order of magnitude for the H-.-induced reduction of the sulfoxide moiety. Electrochemical cyclic voltammetry experiments on the oxidation of RS(CH2)(n)SR', RS(CH2)(n)SOR', RSO(CH2)(n)SOR', and RS(CH2)(n)SO2R' showed relatively little influence of the sulfur-linking alkyl chain length and the nature of the terminal alkyl substituents except for the dithiaalkanes. This may indicate the lack of any significant electronic interaction between the S and SO moieties in the alkylsulfinyl sulfides, SO and SO, in the bis(alkylsulfinyl)alkanes, and S and SO2 in the alkylsulfonyl sulfides. The electrochemical data further suggest that, concerning RS(CH2)(n)SOR', the lower oxidation potential pertains to the oxidation of the sulfide moiety (yielding RSO(CH2)(n)SOR'). The SO --> SO2 oxidation, on the other hand, requires potentials which are more positive by about 0.2 V. It appears that the RS(CH2)(3)SOR' --> RS(CH2)(3)SO2R' oxidation prevails when R' is electron density releasing, while an electron density releasing R favors the RS(CH2)(n)SOR' --> RSO(CH2)(3)SOR' oxidation.