Zeolite-supported metallic catalysts are very important in the chemistry industry, especially in naphtha related reactions such as dehydrogenation of naphthenics to aromatics and paraffin hidroisomerisation. In the Pt/KL-zeolite catalyst the size and dispersion of the metallic particles are fundamental parameters for its performance [1,2]. Different methods of metal introduction are employed to achieve the desired properties. In the present work, samples prepared by ionic exchange (IE) and wet point impregnation (WPI) were analyzed.The metallic particles are nm-sized and thus TEM is required for their characterization [2]. However, as shown in Figure 1, it is not an easy task to discriminate the particles in a TEM image, due to the strong changes in contrast that result from the varying thickness of the zeolite support.