The objective of this paper is to display the results of the flotation and adsorption behaviors of benzo-hydroxamic acid (BHA), potassium amyl xanthate (KAX), dodecylamine- hydrochloride (DDA), mixed BHA/DDA and KAX/DDA on smithsonite. The flotation results show a collecting ability sequence of BHA > KAX > DDA on smithsonite and the best flotation performance at mixing ratio of 1:4 mol fraction DDA/KAX for mixed collector on smithsonite. The enhancement of smithsonite recovery by co-adsorption of KAX and DDA, while no promotion effect as to mixed BHA/DDA catanionic system, are attributed to the difference in steric effect of absorbed head group. According to the results of zeta potential and contact angle (CA) measurements, a most negative charged and the highest hydrophobic smithsonite surface are attained using KAX with DDA as co-collector, which shows a good agreement with the flotation results. FTIR measurements display the stabilization against oxidation and decomposition of DDA on KAX and the inhibition of preferential adsorbed BHA ions on DDA adsorption. The interaction energies of single and mixed collectors with mineral surface also shows well consistency with experimental results. The adsorption models proposed illustrate the decrease in the electrostatic head-head repulsion and the increase in lateral tail-tail hydrophobic interaction between adjacent KAX anions due to the insertion of DDA cations, while almost no DDA could access to smithsonite surface through adjacent BHA owing to steric effect. (C) 2017 Elsevier B.V. All rights reserved.