In this paper, the synthesis of iron pyrite nanoparticles (FeS2) is investigated both experimentally and numerically through facile hydrothermal route in a laboratory-scale stirred autoclave reactor equipped with a 4-bladed 45 degrees pitched-blade turbine (PBT) impeller. An elaborated CFD model is also adopted which accounts for the governing transport phenomena, namely mass, momentum, energy and species equations to investigate flow behavior as well as mixing patterns and chemical reactions for the synthesis of iron pyrite nanoparticles in the autoclave reactor. The iron pyrite reactor is described as an incompressible, single-phase, liquid mixing regime undergoing chemical reactions via integrating with an appropriate proposed kinetics model obtained experimentally. Power consumption and mixing time of the autoclave reactor are measured experimentally to assess the validity of the CFD model. Besides, the effect of temperature and reactant molar ratio as two important key parameters in the synthesis reaction is evaluated both numerically and experimentally, and the products in each scheme are characterized by X-ray diffraction (XRD) analysis. Both cold and reactive simulated results are in good agreement with experiments carried out in this work. Moreover, the reactive simulated results in conjunction with the XRD measurements illustrate that temperature is not an influential parameter in the synthesis of iron pyrite; whereas, an appropriate value of the reactants molar ratio is required to obtain a more purified product. The present developed CFD model is anticipated to help researchers in better understanding of the synthesis process, and to be useful as a bridge to the pilot-plant design in a cost-effective way. (C) 2015 Elsevier B.V. All rights reserved.