BaMgAl10O17 (BMA) solid has been prepared by a sol-gel process: after calcination at 1200 degreesC a regular structure is obtained along with BET area of 13 m(2) g(-1). Unexpectedly this solid is active in the catalytic combustion of methane, and its activity is comparable to the activity of other hexaaluminates containing transition metal ions. This activity may be due to oxygen ion diffusion through the mirror plane in relation with a charge compensation mechanism induced by the presence of Mg2+ ions. The introduction of Mn ions does not alter the structure but leads to the same phenomenon due to the presence of Mn2+ ions. A minor amount of Mn3+, revealed by hydrogen TPR and by reflectance spectroscopy, is responsible for an enhanced oxidation activity and a lowering of the activation energy. Such BMA materials may have interesting properties as oxidation catalyst.