A novel organic compound acetic acid-[(hydrazinylthioxomethyl)thio]-sodium was synthesized andcharacterized. Theflotation performance and adsorption mechanism of AHS to galena were investigatedby micro, benchflotation tests, UV spectra, zeta potential, FTIR and XPS measurements. The resultsdemonstrated that AHS exhibited superior depressing power to galena and could be used as selectivedepressant forflotation separation of molybdenite from galena. The results of UV spectra, FTIR, zetapotential and XPS measurements demonstrated that AHS chemisorb on galena surface by formingfivememberedcheat ring with releasing of H ions. Therefore, the possible adsorption mode of AHS on galenasurface was recommended.