Hydrolysis of isothiouronium salts gives thiols.
:[RSC(NH)]X + NaOH → RSH + OC(NH)  + NaX
Isothiouronium salts in which the sulfur has been alkylated, such as S-methylisothiourea hemisulfate (CAS number: 867-44-7), will convert amines into guanidinium groups. This approach is sometimes called the Rathke synthesis after Bernhard Rathke who first reported it in 1881.
: RNH + [MeSC(NH)]X → RNC(NH)]X + MeSH
Chelating resins with isothiouronium groups are used to recover mercury and other noble metals including platinum from solutions.