We will report on recent computational and experimental progress in developing microkinetic models. On the computational side, we are developing a generic Kinetic Monte Carlo (KMC) module and a module for identification of probable elementary reaction steps. These modules will enable a theoretical description of heterogeneously catalyzed processes, in which numerous elementary chemical reaction steps compete with each other at various active sites over catalyst surfaces. The KMC module will be applicable to well-defined crystallographic structure surfaces and any compositions and patterns of the mixed metallics. In the second module, for identification of probable elementary reaction steps, we will expand and implement recent methodological advances in modeling of infrequent events. On the experimental side, we are developing a new capability for performing detailed transient kinetics studies to probe catalytic reaction mechanisms, while simultaneously spectroscopically characterizing the chemical state of adsorbed species on the catalyst surfaces. The core capability developed under this project will enable the development of a steady-state isotopic transient kinetic analysis (SSITKA) capability to enable a kinetic description of processes to be modeled. Our proposed approach is unique in that we propose an in situ spectroscopic probe of adsorbed reactants/intermediates/products on the catalyst materials. In principle, the spectroscopic interrogation will enable us to postulate feasible reaction mechanisms, whereas the SSITKA analysis will enable us to test these proposed mechanisms by providing quantitative kinetic rate parameters. These new tools will enable us to ascertain reaction mechanisms, provide quantitative kinetic rate parameters for elementary reaction steps, and allow evaluating performance of catalysts at the micro- and meso-scales.