The present disclosure relates generally to catalyst materials and processes for making and using them. More particularly, the present disclosure relates to molybdenum, bismuth and iron-containing metal oxide catalyst materials useful, for example, in the partial oxidation or ammoxidation of propylene or isobutylene, processes for making them, and processes for making acrolein, methacrolein, acrylonitrile, and methacrylonitrile using such catalysts.