First-principles calculations for heterogeneously catalysed reactions have emerged as a major source of information for understanding the underlying reaction mechanism. Combining computational chemistry derived insights with experimentally measured reaction rates and reaction orders, along with input from spectroscopies and materials characterization techniques can lead the quest for the nature of the active site. In this ceminar, utilizing the example of formic acid (HCOOH) decomposition on late transition metal surfaces, we will demonstrate how one can determine the nature of the active site and what is on the catalyst’s surface under reaction conditions, through mean-field microkinetic modeling. The notion of self-consistent microkinetic model will be introduced. By elucidating the reaction mechanism on different metals and various facets of those, we develop scaling and Bronsted-Evans-Polanyi correlations allowing for the atomic-scale design of improved catalysts targeting selective dehydrogenation of HCOOH on shape-selected and alloy nanoparticles.