The melting diagram of the system dimethylsulfide-hydrogen chloride has been determined using difference thermal analysis. It shows the existence of three adducts Me2S . nHCl with n = 1, 4 and 5 as well as melting points of -91, -53 and -80-degrees-C (decomposition), respectively. The two phases richest in HCl have been further characterized by crystal structure analysis. Me2S . 4HCl is orthorhombic with space group Pnma and Z = 4 formula units per unit cell of dimensions a = 14.842, b = 9.747 and c = 6.652 angstrom at -150-degrees-C. Me2S . 5HCl is monoclinic with P2(1)/n and Z = 4 as well as a = 7.292, b = 12.537, c = 12.479 angstrom and beta = 92.73-degrees at -168-degrees-C. The R values obtained with 1737 and 3047 independent observed reflections are 0.039 and 0.045, respectively. Both structures are ionic, according to [Me2SH][Cl(HCl)n-1], and shaped by hydrogen bonding.