Abstract: Activated carbons (AC) were obtained through carbonization of polyaniline and modified lignosulfonate composite (PAn-MLS) under different temperatures; they are characterized by fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, nitrogen sorption and scanning electron microscope (SEM). With these carbon materials as the support, a series of Pd-AC catalysts for the oxidation of formic acid were prepared by liquid phase reduction and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and electrochemical analysis. The results show that with the activated carbon prepared at 800℃ (AC800) as the support, the Pd-AC800 catalyst obtained performs best in the oxidation of formic acid; the palladium particles have an average size of 5.4 nm and the electro-active surface area reaches 53.78 m²/g. As the oxidation of formic acid over Pd-AC800 is realized through direct pathway rather than CO pathway, Pd-AC800 may be considered as a potential electrode material in direct formic acid fuel cells (DFAFC).