To control acid mine drainage (AMD) at the source, a novel nanocomposite coating, based on SiO2 nanoparticles as nanofiller embedded in gamma-mercaptopropyltrimethoxysilane (PropS-SH) coating is introduced in this paper. The performance of the PropS-SH/SiO2 (PSS) nanocomposite coatings with a different content of SiO2 nanoparticles on pyrite oxidation inhibition was evaluated by electrochemical measurements and chemical leaching testing. The results of the investigations revealed that the addition of appropriate SiO2 nanoparticles could greatly enhance the passivation efficiency of PropS-SH coating. The best coating was obtained from 3% (v/v) of PropS-SH solution with 2 wt% SiO2 nanoparticles as this coating decreased pyrite oxidation by 81.1% (based on Fe release). In addition, the coating mechanism of PSS coatings on pyrite surfaces is presented in this paper. (C) 2017 Elsevier B.V. All rights reserved.