The electrochemical behaviour of laboratory prepared manganese dioxide with different additions of aluminium has been investigated. The findings have been compared with the ones found for commercial samples. All samples have been submitted to X-ray diffraction measurement. The electrochemical reduction has been carried out in 1 and in 9 M KOH electrolytes, by means of slow rate voltammetric tests. Interesting correlations have been found between the results of the physico-chemical characterisation and the electrochemical behaviour. Among other beneficial effects, aluminium seems to improve the quality and uniformity of the contact between the dioxide surface and gaphite, thus increasing the conductance of the mass and the amount of dioxide available for the reduction. Examination of the samples surface has revealed that such effect is tied to the specific kind of morphology induced by aluminium. (C) 2001 Elsevier Science B.V All rights reserved.