The aim of this paper is to review the catalytic reactions for the removal of NO and, more particularly, to discuss the reduction of NO in the presence of NH3, CO, H-2 or hydrocarbons as well as the decomposition of NO. The nature of the different active species, their formation due to dispersion and their interaction with different supports as well as the corresponding correlations with catalytic performance are also discussed. Another goal of this review is to explain the mechanism and kinetics of these reactions on different surfaces as well as the catalyst stability.