An important part of a general simulation model of the Thermal DeNO(x) process is the detailed kinetic mechanism used to represent all the interconnecting reaction paths. Unfortunately, the location and dimension of the operating window investigated experimentally to validate a detailed kinetic mechanism strongly influences the reliability of its predictions, and explains the large differences occasionally found among the predictions of different mechanisms. Therefore. it is important to produce new sets of data kinetically significant to investigate the behavior of these models in different conditions, with particular reference to well-stirred conditions that are usually not considered in the literature. This paper presents the results of some experiments carried out in a laboratory jet-stirred reactor at atmospheric pressure and in the range 950-1450 K. Such experimental results enlarge the operating window available for model validation since they involve well-stirred conditions and the presence of both carbon monoxide and water. Then, they have been used. together with other experiments previously presented in the literature, to validate a detailed kinetic mechanism. Such a mechanism has been proved to be able to predict experiments performed not only in plug-flow conditions but also in well-stirred one.