Bunsen reaction is one of the three reaction steps of iodine-sulfur process. In present study, Bunsen reaction is carried out in co-current reactor to identify effect of different operating conditions on concentrations of Bunsen reaction product mixture. Bunsen reaction studies have been done in tubular reactor, which is made of tantalum tube and stainless steel jacket, in 50-80 degrees C temperature range, 2-6 bar (g) pressure range. Feed flow rates are varied for HIx (mixture of hydroiodic acid, water and iodine) 1.2 1/h - 3 I/h, SO2 0.02 g/s - 0.24 g/s and O-2 0.008 g/s -0.016 g/s. It has been observed that, increasing SO2 feed flow rate and pressure results in increased mole fraction of HI in HIx phase and H2SO4 in sulfuric acid phase. Increase in temperature increased the mole fraction of HI in HIx phase but decreased the mole fraction of H2SO4 in sulfuric acid phase. Increase in feed I-2/H2O ratio and HIx feed flow rate, decreased the mole fraction of HI in HIx phase. Higher pressure improved the conversion of Bunsen reactants to products. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.