This work shows the stepwise improvement of air electrodes by the right combination of catalysts. In all electrodes carbon nanotubes serve as carbon support. The electrodes are produced by ultrasonic mixing of the carbon nanotubes and the catalysts. Their catalytic activity towards oxygen reduction in alkaline solution is evaluated by polarisation curves and electrochemical impedance spectroscopy. In a first step La1-xSrxMnO3 perovskites are investigated, as well as La0.65Sr0.35MnO3 and La0.6Sr0.4CoO3 are compared. It is found that La0.65Sr0.35MnO3 and La0.6Sr0.4CoO3 have a positive impact on different parts of the current-potential curve. In a second step the influence of small amounts of platinum as an additional catalyst besides the perovskite is analyzed with the result that platinum lowers significantly the activation polarisation. Finally, the optimum composition of the electrode is found by using the synergetic effect of platinum, La0.65Sr0.35MnO3 and La0.6Sr0.4CoO3. (C) 2010 Elsevier B.V. All rights reserved.