Adsorption kinetics of an organic-inorganic hybrid polymer, Al(OH) 3-polyacrylamide (Al-PAM), on silica and alumina were studied by a dissipative quartz crystal microbalance (QCM-D). The effects of molecular weight and aluminum content of Al-PAM on its adsorption at varying solution pH were investigated. For comparison, the adsorption of a commercial partially hydrolyzed polyacrylamide, Magnafloc1011 (MF1011), on both silica and alumina was also studied. For Al-PAM of a given molecular weight and aluminum content, the adsorption of Al-PAM on both silica and alumina was found to be highly dependent on polymer concentration and solution pH, showing stronger and more rapid adsorption on silica than on alumina within the pH range studied. Adsorption rate of Al-PAM on silica was observed to increase with increasing molecular weight and aluminum content, while Al-PAM of lower aluminum content adsorbed more favorably on alumina. Commercially available MF1011 showed negligible adsorption on silica but a stronger affinity to alumina than Al-PAM. The results of polymer adsorption determined by QCM-D correlated well with flocculation results of silica and alumina with Al-PAM and MF1011 as flocculants. Atomic force microscopic imaging revealed the morphology of polymers adsorbed on silica and alumina. © 2011 American Chemical Society.