In this study, a series of batch flotation experiments was conducted to evaluate both the role of particle size distribution and the presence of sodium metabisulfite Na2S2O5 (SMBS) in chalcopyrite and pyrite flotation. Kinetic flotation tests were also carried out in order to evaluate the kinetics behavior of the above-mentioned minerals. Following this, different flotation kinetics models were compared to the data from the experiments. According to the obtained results, it can be stated that feed particle size distribution plays a greater role in chalcopyrite and pyrite grades rather than their recoveries. However, the contribution of SMBS is higher than that of particle size with respect to pyrite recovery. In this study, the maximum recoveries for chalcopyrite and pyrite were found to be 92.2% and 47.5%, respectively. The minimum pyrite recovery (13.47%) occurred in the presence of 40g/t Xanthate-flomin (C-4132), 20g/t methyl isobutyl carbonyl (MIBC), 20g/t polypropylene glycol (F742), 200g/t sodium metabisulfite (SMBS), and at a d(70) of 70 mu m. A comparison between several flotation kinetics models and the experimental data revealed that the perfect mixer and the Arbiter models showed completely similar results for both chalcopyrite and pyrite with respect to the use of different configuration of chemical reagents.