The influence of the degree of substitution of the cobalt and manganese ions into AlPO-18 structure was investigated for the conversion of methanol to light olefins (MTO) at 350 degreesC. The results show that the activity for methanol conversion increases with transition metal content up to 2 at.% for conversion of methanol after 2 h on stream. These catalysts show good stability for this reaction after regeneration suggesting that there is no leaching of the active metal centres. (C) 2003 Elsevier B.V. All rights reserved.