Abstract Previous studies showed the adequate efficiency of green corrosion inhibition of 1018 carbon steel in 0.5 M H2SO4 by garlic extract (Allium sativum) in static conditions at 25 °C. In this condition, the inhibition efficiency was 95 % at 400 ppm. Another study under similar conditions, showed an inhibition efficiency of 80% for 1045 steel (with 800 ppm inhibitor) and 70% for 1080 steel (with 400 ppm inhibitor). Here, the effect of dynamic conditions in the corrosion inhibition by garlic extract for these steels exposed in 0.5 M H2SO4 at 25 °C was investigated. In order to investigate the effect of dynamic conditions, a rotating cylinder electrode was used at 0, 250, 500, 1000 and 2000 rpm. The inhibitor efficiency was obtained by potentiodynamic polarization measurements and spectroscopy electrochemical impedance. The results indicated that the green inhibitor efficiency behaves somewhat different for both carbon steels in particular at 2000 rpm. In this condition, the inhibition efficiency was 77% for the 1080 carbon steel and 95 % for the 1045 carbon steel. According to the electrochemical tests in the present work, it seems that the garlic extract acts for both steels as a mixed type green inhibitor. This research shows that the garlic extract is a good candidate as a green inhibitor to be used in new possible environmental friendly corrosion inhibitor formulations