Bawang Lanang dengan nama ilmiah “Allium Sativum solo garlic” dapat di pergunakan sebagai inhibitor organik karena dapat menurunkan laju korosi logam dan ramah lingkungan. Material yang di gunakan adalah plat baja hitam termasuk baja karbon rendah yang rentan dan cepat terkena korosi di lingkungan air laut. Laju korosi logam dan efesiensi inhibitor didapatkan dari uji weight loss selama interval 5 hari, 10 hari, 15 hari, 20 hari, 25 hari dan 30 hari. Variasi inhibitor yang digunakan yaitu 0 ppm, 50 ppm, 100 ppm, 150 ppm, 200 ppm. Sedangkan mekanisme kerja inhibitor di analisa melalui uji foto makro dan uji FTIR. Berdasarkan pengujian 4 konsentrasi inhibitor tersebut diperoleh hasil terbaik dan terburuk. Hasil uji weight loss dan efisiensi menunjukkan nilai laju korosi tertinggi dengan penambahan inhibitor Allium sativum solo garlic sebesar 200 ppm yaitu 0,12 mm/year, dengan efisiensi terendah 15,39%. Sedangkan nilai laju korosi terendah dengan penambahan inhibitor Allium sativum solo garlic sebesar 100 ppm yaitu 0,06 mm/year dengan efisiensi tertinggi 56,78%. Mekanisme kerja inhibitor agar dapat melindungi plat baja hitam dari korosi dalam lingkungan air laut. Inhibitor Allium sativum solo garlic dapat teradsorpsi pada permukaan plat baja hitam dan juga dapat menurunkan laju korosi.

single clove garlic (Allium sativum solo garlic) can be used as an organic inhibitor to prevent the corrosion rate of the metal, and it is surely nature-friendly. the material tested in the studiy is black steel plate, a low-carboned steel which is easily corroded in the sea water environment. The parametet for corrosion rate and the inhibitor efficiency was the weight lost test in the intervals of 5, 10, 15, 20, 25 and 30 days. The variants of inhibitor applied here was 0 ppm, 50 ppm, 100 ppm, 150 ppm, 200 ppm. The work mechanism of the inhibitor was analyzed through macro photography and FTIR test. Based on the analysis of the variants by weight loss and efficiency tests, the highest rate of the corrosion is found in the 200-ppm variant, with 1.05 mm/year, and its lowest efficiency of 15.53%. Meanwhile the slowest corrosion is identifiend from the 100-ppm variant, only 0.54 mm/year and its highest efficiency of 57.43%. The work mechanism of the inhibitor has been proved to protect the steel plate from corrosion in the sea water environment. The natural inhibitor can be adsorbed on the plate surface and reduce the corrosion rate.