The ultimate purpose of the Catalytic Preconverter Vibration Program is the development of a method for evaluating and improving in-service mechanical robustness of ceramic catalytic converters. The program focuses on preconditioned and thermally aged close-coupled preconverters which may be subject to severe in-service engine and exhaust system vibrations. From a mechanical durability point of view, characterization of the substrate vibration response in the preconverter can is necessary to predict the possibility of adverse in-service substrate resonances. The substrate dynamic response was determined for preconverters canned with an intumescent mat material. Room temperature vibration measurements of preconditioned and thermally aged preconverters are presented. These vibration resonances were favorably correlated with static hot push-test results verifying the ability of a static measurement technique to predict dynamic response. Vibration response as a function of operating temperature, using a novel high temperature vibration test method, is also shown.Due to the severe operating environment, vibration measurements during actual vehicle installation can only be obtained outside the converter can. A prototype design for in-service vibration measurements is presented herein. Future use of the prototype design which can provide vibration measurements of the internal substrate and exterior canister is recommended to absolutely determine vibration input and preconverter substrate response in the severe operating environment.