Experimental results describing the product distribution during the reduction of NO by H 2 on Pt/Al 2 O 3 and Pt/BaO/Al 2 O 3 catalysts are presented in the temperature range 30–500°C and H 2 /NO feed ratio range of 0.9–2.5. A microkinetic model that describes the kinetics of NO reduction by H 2 on Pt/Al 2 O 3 is proposed and most of the kinetic parameters are estimated from either literature data or from thermodynamic constraints. The microkinetic model is combined with the short monolith flow model to simulate the conversions and selectivities corresponding to the experimental conditions. The predicted trends are in excellent qualitative and reasonable quantitative agreement with the experimental results. Both the model and the experiments show that N 2 O formation is favored at low temperatures and low H 2 /NO feed ratios, N 2 selectivity increases monotonically with temperature for H 2 /NO feed ratios of 1.2 or less but goes through a maximum at intermediate temperatures (around 100°C) for H 2 /NO feed ratios 1.5 or higher. Ammonia formation is favored for H 2 /NO feed ratios of 1.5 or higher and intermediate temperatures (100–350°C) buts starts to decompose at a temperature of 400°C or higher. The microkinetic model is used to determine the surface coverages and explain the trends in the experimentally observed selectivities.