Microkinetic analysis is a powerful tool for elucidating the catalytic surface chemistry of a variety of reactions. Starting with a detailed description of the elementary reaction steps, a thorough quantitative microkinetic analysis of the transient and steady-state experiments is performed. The resulting microkinetic models can be used to bridge the pressure and material gaps between results collected on well-defined single crystals under ultra-high vacuum conditions and on supported-metal commercial catalysts under industrial conditions. This approach will be presented for the ammonia synthesis reaction catalyzed by ruthenium. The reasons that this microkinetic analysis works so well will be explored in this contribution. (C)1999 Elsevier Science B.V. All rights reserved.