Abstract: The porous structures and their evolution of graphitic cathode materials at various baking temperatures were investigated using the image analysis method. The porous structure parameters, such as porosity, pore size distribution, aspect ratio, specific surface area, and pore connectivity, were statistically calculated and the fractal features showing the degree of porous complexity were also analyzed. It is found that the porosity increases with increasing baking temperature, while the specific surface area, aspect ratio, and connectivity first decrease and then increase. The porous structure evolution of graphitic cathodes abides by the law of fractal behaviors and hence an evolution model has been proposed. This result indicates that the image analysis parameters and the fractal dimension can apply for characterizing the degree of porous structure evolution when subjected to a given baking temperature.