The invention relates to a catalyst composition, a method of making the same and its use in the conversion of a feedstock, preferably an oxygenated feedstock, into one or more olefin(s), preferably ethylene and/or propylene The catalyst composition comprises a molecular sieve and at least one metal oxide, such as a magnesium oxide that, when saturated with acetone and contacted with said acetone for 1 hour at 25.degree. C., converts more than 80% of the acetone.