Abstract: Two oil soluble organic thioantimonials, antimony tri-dodecyl mercaptide and antimony tri-α-naphthylethyl mercaptide, have been prepared by modifying Clemenca and Leffler's procedure. Antimony tri-dodecyl mercaptide was easily obtained from dodecyl mercaptan and antimony trichloride in methanol. It was separated immediately from the solution as colorless crystals of melting point 45-46℃ (literature, 38-40℃). Antimony tri-α-naphthyl ethyl mercaptide was obtained from α-naphthylethylmercaptan and antimony trichloride in ether. After removing the solvent, drying, and then washing with methanol and ether, we obtained a white solid of melting point 69-70℃, while the product as given in literature was an oil or a waxy solid. α-Naphthylethylmercaptan was prepared by hydrolyzing the product obtained from α-naphthylethyl bromide and thiourea in aqueous solution. It was better to separate the intermediate, α-naphthylethyl isothiouronium bromide from the solution, and then to hydrolyze the purified product in alkaline solution under nitrogen atmosphere to obtain the pure mercaptan. Both thioantimonials have been proved to possess the therapeutic action in the treatment of experimental infections of schistosoma japonicum in mice.