The effects of flow rate and temperature on the corrosion behaviour of the Al-2.5 Mg alloy in a 3% NaCl solution and the inhibiting efficiency of (+)-catechin on the corrosion of the same alloy have been examined. Measurements were carried out in a flow-through cell, at different flow rates (v (1) = 0.0029 m s(-1), v (2) = 0.0059 m s(-1) and v (3) = 0.0118 m s(-1)) and temperatures (20, 30, 40 degrees C). Electrochemical parameters for the Al-2.5 Mg alloy were determined by polarisation techniques and electrochemical impedance spectroscopy (EIS). Increased flow rate and temperature cause a stronger corrosion attack on the alloy. The addition of (+)-catechin inhibited corrosion at all temperatures and flow rates. The inhibitor efficiency decreased with increase in flow rate and temperature.