Ignition systems are one of the key technologies to achieve cost/performance/emission characteristic goals for lean and stoichiometric industrial natural gas reciprocating engines. In natural gas applications spark breakdown voltages are very high requiring small and consistent gaps for reliable ignition. As a consequence erosion and corrosion of spark plug electrode materials is a major issue as excessive electrode wear results in costly downtime for spark plug replacement. As cylinder pressures, compression ratios, and ignition voltages are increased, and conditions further move towards leaner burning combustion, spark plug reliability and lifetime performance will become even more critical and could limit further advances in engine development. The near-term goal of this work is to characterize used spark plugs after a variety of field service and/or controlled engine test conditions to gain insight into the electrode corrosion/erosion processes that limit the spark plug lifetime. The long-term goal is to design new electrode materials based on a fundamental understanding gained from this characterization work.