A xanthation-modified polyacrylamide (PAM), named PAM-X, was synthesized. In single mineral flotation tests. PAM-X exhibited unique selectivity between galena and Cu-activated sphalerite. The adsorption mechanisms were investigated via attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). It was observed that PAM-X had different absorption band shifts when adsorbed onto galena and Cu-activated sphalerite, indicating the formation of different adsorption bonds between PAM-X and the minerals. The analysis by ATR-FTIR and X-ray photoelectron spectroscopy (XPS) revealed that PAM-X was a mixture composed of partially hydrolyzed PAM and a low molecular weight sulfur-bearing compound. The observed selectivity of PAM-X to galena and Cu-activated sphalerite was attributed to the adsorption of the PAM-X and the synergistic effect of its two components. (C) 2012 Elsevier Ltd. All rights reserved.