1,2-Mercapto alcohols and 1,2-mercapto amines proved to be useful reagents towards Michael acceptors, such as α,β-ethylenic ketones, esters and nitriles leading to variously polyfunctionalized unsymmetric sulfides. Reaction of 1,2-mercapto alcohols with electron-deficient alkynes allowed to obtain β-hydroxy vinyl sulfides as valuable precursors of 1,3-oxathiolane derivatives. Extension to β-hydroxy selenols resulted in the isolation of unsymmetric selenides, formed through a Se-alkylation. [ABSTRACT FROM AUTHOR]