BACKGROUND: A batch electrochemical reactor with a rotating cylinder electrode is analysed for the transformation of sulfur dioxide into either sulfuric acid or colloidal sulfur. RESULTS: Potentiostatic experiments carried out at 30 degrees C and 500 rpm with 5 g L-1 SO2 in 0.5 mol L-1 H2SO4 conclude that-0.7 V, against SCE, represents an appropriate potential for the sulfur production at a 316 L stainless steel cathode. The figures of merit were: 0.15 kg m(-3) h(-1) space time yield and 39.7 kWh kg(-1) for specific energy consumption. Galvanostatic experiments at 30 degrees C and 1000 rpm with three-dimensional electrodes identify graphite felt as a promising anodic material. Using a gas phase of 5% SO2 in nitrogen and 0.5 mol L-1 H2SO4 as supporting electrolyte, a macrokinetic current density of 100 mA cm(-2) represents an appropriate value, being the space time yield 7.58 kg m(-3) h(-1) with 2.86 kWh kg(-1) specific energy consumption. CONCLUSION: An electrochemical reactor with a rotating cylinder electrode showed a good performance for the production of colloidal sulfur. Sulfur dioxide was also converted into sulfuric acid including a separator in a reactor with a three-dimensional rotating cylinder anode and co-current gas and liquid flows. (C) 2014 Society of Chemical Industry