Carbon films were developed from polyacrylonitrile (PAN) modified with cobalt chloride. The modification was carried out by immersing PAN in a 5% cobaltous chloride (CoCl2) solution at 90 degrees C for 5 min, oven-dried, and then manufactured into films. The original and modified PAN films were oxidized at 220 degrees C for 2 and 6 h in air, respectively, and finally carbonized at 1300 degrees C. The density, microstructure, elemental analyzer, electrical conductivity, and morphology were all studied. According to the results, it was found that films modified with cobalt chloride have a greater stacking height of carbon-layer planes (L-c), density, electrical conductivity, and nitrogen content after carbonization. Moreover, during the carbonization stage, the cobalt ions promote a catalytic action. The carbon films developed from the modified film not only improved electrical conductivity by 12-38%, but also increased tensile strength by 29-36% and the tensile modulus by 69-110%. Therefore, carbon films having better mechanical properties can be obtained after such modification.