Morphology and distribution of carbon deposit accumulated in Pd/CeO2 catalyst, Pd black and Pd3Ce alloy during heating in ethylene at 873 K was studied by transmission electron microscopy (TEM) and selected area electron diffraction (SAED). In Pd/CeO2 catalyst filamentous carbon was formed, with microstructure depending strongly on temperature of the catalyst reduction in hydrogen. Samples reduced at 673 and 773 K produced filaments exhibiting "whisker-like" mode of growth (metal particles were located at the tip of the filaments), while whose reduced at 973 and 1100 K produced "extrusion-like" filaments (Pd particles were located at the bottom, attached to ceria crystallites). Reduction of the Pd/CeO2 catalyst at 1200 K hindered completely the formation of carbon filaments. Extensive carbon, deposit in the form of whiskers and shells occurred in Pd black, while no carbon deposition was observed in Pd3Ce alloy. The change in the filament growth mode with increasing temperature of reduction has been explained by increasing strength of the Pd-ceria interaction (epitaxial orientation of Pd particles on CeO2, decoration of Pd surface with partly reduced ceria species and formation of Pd-Ce alloy).