Synthesis of wurtzite-type ZnS nanoparticles by an electric discharge submerged in molten sulfur is reported. By the pulsed plasma between two zinc electrodes of 5 mm diameter in molten sulfur, we have synthesized high-temperature phase (wurtzite-type) ZnS nanocrystals with an average size of about 20 nm. Refined lattice parameters of the synthesized wurtzite-type ZnS nanoparticles were found to be larger than those of the reported ZnS (JCPDS 36-1450). UV-Visible absorption spectroscopy analysis showed that the absorption peak of the as-prepared ZnS sample (319 nm) displays a blue-shift comparing to the bulk ZnS (335 nm). Photoluminescence spectra of the samples revealed peaks at 340, 397, 423, 455 and 471 nm, which were related to excitonic emission and stoichiometric defects. Synthesis of ZnMgS (solid solution of ZnS and MgS) was achieved by using ZnMg alloys as both cathode and anode electrodes. Also, rocksalt structure MgS was synthesized by using magnesium rods as both cathode and anode electrodes.