This proposal aims to elucidate the environment-dependent mechanism of a novel Pd single atom catalyst (SAC), whose dynamic and switchable reactivity we have observed for the very first time in the field, during thermocatalytic Miyaura borylation of aryl halides and Suzuki coupling. Using operando quick XANES and EXAFS, we will investigate how the catalyst undergoes real-time changes in oxidation state, coordination environment, and geometry in response to variations in the chemical environment, specifically the strength of the base. The findings will enable us to shed light into the tunability of SACs and the pivotal role of the chemical environment in modulating their activity.