BACKGROUND: This work analyses the performance of a batch electrochemical reactor with a three-dimensional rotating cylinder cathode for the synthesis of alkaline peroxide by reduction of O-2 under 0.1 MPa (abs). The centrifugal force produces a radial co-current flow of the gas and liquid phases through the cathode achieving good mass-transfer conditions for the O-2 reduction. RESULTS: Galvanostatic experiments carried out during 2 h at 2 A (macrokinetic current density 398 A m(-2)), 30 degrees C and 1000 rpm with 1 mol L-1 H2SO4 as anolyte demonstrates that the cationic exchange membrane Nafion (R) 415 is an appropriate separator. However, a small decrease in the alkalinity of the cathodic compartment was observed. The use as anolyte of an equimolar solution of Na2SO4 and H2SO4 (1 mol L-1) maintains constant the total alkalinity of the cathodic solution. An experiment of 6 h yielded 10.3 g L-1 H2O2 concentration with 62.3% current efficiency and 10.6 kWh kg(-1) specific energy consumption, using Na2SiO3 as addition agent. CONCLUSION: A divided electrochemical reactor using an acid anolyte and a three-dimensional rotating cylinder cathode with co-current oxygen and liquid flows represents a simple strategy for localized generation of peroxide solutions with low total alkalinity. (C) 2014 Society of Chemical Industry