Abstract The charge state of supported metal catalysts is the key to understand the elementary processes involved in catalytic reactions. However, high-precision charge analysis of the metal catalysts at the atomic level is experimentally challenging. To address this critical challenge, high-sensitivity electron holography has recently been successfully applied for precisely measuring the elementary charges on individual platinum nanoparticles supported on a titanium dioxide surface. In this review, we introduce the latest advancements in high-precision charge analysis and discuss the mechanisms of charge transfer at the metal–support interface. The development of charge measurements is entering a new era, and charge analyses under conditions closer to practical working environments, such as real-time, real-space, and reactive gas environments, are expected to be realized in the near future.