The Lewis basic lone pairs on sulfur dominate the sulfides' reactivity.  Sulfides readily alkylate to stable sulfonium salts, such as trimethylsulfonium iodide:
Sulfides also oxidize easily to sulfoxides (), which can themselves be further oxidized to sulfones (). Hydrogen peroxide is a typical oxidant—for example, with dimethyl sulfide ():
In analogy to their easy alkylation, sulfides bind to metals to form thioether complexes. Consequently Lewis acids do not decompose thioethers as they do ethers.  Sulfides are soft ligands, but their affinity for metals is lower than typical phosphines. Chelating thioethers are known, such as 1,4,7-trithiacyclononane.  
Sulfides undergo hydrogenolysis in the presence of certain metals:
Raney nickel is useful for stoichiometric reactions in organic synthesis whereas molybdenum-based catalysts are used to "sweeten" petroleum fractions, in the process called hydrodesulfurization.
Unlike ethers, thioethers are stable in the presence of Grignard reagents.  The protons adjacent to the sulfur atom are labile, and can be deprotonated with strong bases.