The invention relates to a conversion process of a feedstock, preferably an oxygenated feedstock, into one or more olefin(s), preferably ethylene and/or propylene, in the presence of a molecular sieve catalyst composition that includes a molecular sieve and a Group 3 metal oxide and/or an oxide of a Lanthanide or Actinide series element. The invention is also directed to methods of making and formulating the molecular sieve catalyst composition useful in a conversion process of a feedstock into one or more olefin(s).