Catalytic reforming of naphtha for improving its characteristics is one of the most important petroleum refining catalytic processes. Modern catalytic reformers utilize dual function platinum-based catalysts which during operation are exposed to the formation of carbonaceous deposits causing gradual deterioration of their activity and alteration of their selectivity. In-situ regeneration has proved to be adequate practice in restoring a catalyst＇s activity as well as its selectivity. Hence, optimization of regeneration is a vital step of the reforming process. This is usually done under conditions of a general nature that have been recommended by catalyst manufacturers and/or suppliers. Results of thorough laboratory investigations on the thermal behavior of used reforming catalyst (spent samples) revealed that the amount and complexity of the chemical nature of carbonaceous deposits on reforming catalysts are directly related to its life on stream and severity of operating conditions. Optimal regeneration of the catalyst requires specific conditions that take into consideration behavior and combustibility of carbonaceous deposits on its surface. Such information can easily be obtained by applying thermal analysis on catalyst samples which can be taken from the reformer during the production cycle. The paper discusses this topic and presents results of detailed thermal analysis carried out on series of reforming catalyst samples taken from semi-regenerative reformers for two different commercial catalysts.