This chapter summarizes the development and refinement of electrochemiluminescence (ECL) instrumentation, with a focus on achieving single-event detection. It provides an in-depth discussion of advanced instrument design, including high-sensitivity photodetectors, synchronized electrochemical control systems, and optimized signal acquisition techniques. This chapter also presents experimental examples that illustrate the capability of instrumentation to perform in situ ECL spectroscopy, determine absolute quantum efficiency, and, more importantly, capture single ECL events at the nanosecond scale. This discussion underscores the critical role of precision instrumentation in expanding the possibilities of ECL research.