1,3-Propanedithiol is mainly used for the protection of aldehydes and ketones via their reversible formation of dithianes. A prototypical reaction is its  formation of 1,3-dithiane from formaldehyde. The reactivity of this dithiane illustrates the concept of umpolung.  Alkylation gives thioethers, e.g. 1,5-dithiacyclooctane.
The unpleasant odour of 1,3-propanedithiol has encouraged the development of alternative reagents that generate similar derivatives.
1,3-Propanedithiol is used in the synthesis of tiapamil.