The invention relates to a molecular sieve catalyst composition, to a method of making or forming the molecular sieve catalyst composition, and to a conversion process using the catalyst composition. In particular, the invention is directed to a catalyst composition comprising a molecular sieve having a framework including at least [AlO.sub.4] and [PO.sub.4] tetrahedral units, at least one of a binder and a matrix material and at least one phosphorus compound separate from said molecular sieve wherein, after calcination at 760.degree. C. for 3 hours, said catalyst composition has a microporous surface area in excess of 20% of the microporous surface area of said molecular sieve after calcination at 650.degree. C. in nitrogen for 2 hours. The catalyst composition is particularly useful in a conversion process for producing olefin(s), preferably ethylene and/or propylene, from a feedstock, preferably an oxygenate containing feedstock.