Earlier work by us described a group of cobalt ion exchanged zeolites which showed effective performance for the ammoxidation of ethane with NH3/O-2 to acetonitrile, A variety of multidimensional 10 and 12 ring zeolites were the most effective, however, initial efforts using Co-Y zeolite did not display the selectivity and activity one might have expected. The importance of dealumination of Y zeolite is now discussed for the ammoxidation of ethane to acetonitrile in giving much higher activity and selectivity. Process data under a variety of conditions are correlated with physical characterization of these catalysts by FTIR, NMR, and O-2 porosity. Catalyst life studies with these dealuminated catalysts indicate no appreciable decay after more than 100 h of time-on-stream.