The behavior of trace elements during coal combustion varies, depending on their mode of occurrence in a given coal and the variations in the operational conditions in the power plants. However, the extent to Which these variables may influence the behavior of trace elements is not yet clear. The objective of this study is to evaluate the influence of the operational conditions on the behavior of trace elements in two coal-fired power plants when the same coal supply is used Fractions of the fly ash sampled from the hoppers of the electrostatic precipitators (ESPs) were studied and the relative enrichment (RE) factors of the elements were compared. Moreover, a series of leaching tests were carried out, with the objective of determining the level of risk when the wastes are finally disposed of. The behavior of the trace elements was found to be broadly similar. However, some differences were observed when evaluating their distribution among the different fly ash fractions from the,ESPs. These differences are related to (i) the operational variables of the power plants and (ii) the performance of the mills. All Of the coal combustion byproducts evaluated in this work may be considered as inert waste when they are disposed of.