Abstract: The electrochemical corrosion behavior of epoxy heavy-duty coatings immersed in seawater at different temperatures was investigated by electrochemical impedance spectroscopy (EIS). The results show that the increase in capacitance and the decrease in resistance of the coatings both change faster with rising temperature, indicating that higher seawater temperatures accelerate degradation of the coatings. At the initial immersed period, the diffusion process of seawater through the coatings follows the second Fick diffusion law at any seawater temperature and the diffusion activation energy is 49.7 kJ·mol^-1. The diffusion coefficient of seawater across the coatings increases as the seawater temperature rises, and the time for the coatings to reach the maximum water absorption capacity shortens, but the saturated capacity for water absorption of the coatings changes little.