3-Mercapto-5-hydroxy-1,2,4-triazine and 3-mercapto-5-hydroxy-6-methyl-1,2,4-triazine were alkylated in sodium hydroxide solution with methyl iodide, ethyl iodide, or benzyl chloride to give the corresponding 3-methylmercapto-, 3-ethylmercapto-, or 3-benzyl-mercapto-derivatives.The structures of these compounds were proved by hydrolysis with 10% monochloroacetic acid to the corresponding 3,5-dihydroxy derivatives.3-Methyl-mercapto-5-hydroxy-1,2,4-triazine and 3-benxylmercapto-5-hydroxy-G-methyl-1, 2, 4-triazinc can be synthesized directly and in better yields from S-alkyl-isothiosemicarbazide and the appropriate keto acids.