Loss on ignition (LOI) is one of the selected chemical parameters for characterizing the quality of pulverized fuel ashes (PFA). However, this parameter does not represent the unburned carbon in ashes because of the presence of several other compounds which also decompose on heating. In order to evaluate the carbon content in PFA, several thermal analysis methods have been proposed. Thermogravimetric experiments using active/inert atmospheres, high resolution thermogravimetric procedures, and single differential thermal analysis experiments are proposed as new tools for evaluating the presence of unburned carbon and other materials that are also present in PFA, such as calcium carbonate and calcium hydroxide.