We report here on the activity and stability of LaMnO3.15 for the methane combustion, in the absence and presence of H2S, in a temperature interval of 250-750 degrees C. Two powders with different specific surface area were prepared by coprecipitation method using ammonia. Precursors calcined at high temperature, in air, for 10 h have led to LaMn-C solid with S-BET = 11 m(2)/g, while those previously aged in solution (hydrothermal treatment at 200 degrees C under 20 atm. for 24 h) then calcined at high temperature led to LaMn-HydC with S-BET = 31 m(2)/g. Temperature programmed reduction (TPR) profile of both samples showed two main peaks; surface and weakly bound oxygen named alpha-oxygen species and lattice oxygen beta-oxygen species. While for LaMn-C the maximum reduction temperature peak corresponding to alpha-oxygen species was found to be ca. 600 degrees C, for LaMn-HydC samples this peak was shifted to lower temperature ca. 430 degrees C. Indeed, LaMn-HydC samples showed higher depletion of surface and weakly bound oxygen species compared to LaMn-C. The superior catalytic performance of LaMn-HydC in methane combustion was attributed to its high BET surface area and to both the high amount of alpha-oxygen species and their mobility. In the presence of 100 ppm H2S in the feed this catalyst showed a higher propensity to poisoning by sulphur compounds than LaMn-C. This was attributed to the rapid formation of stable sulphate/sulphite species, the decomposition of which occurs above 800 degrees C.