Electrochemical and optical microscopy study of red pepper seed oil corrosion inhibition by self-assembled monolayers (SAM) on 304 SS

•Capsicol was extracted from red pepper seed of Prabu variety.•The inhibition property of the capsicol was studied by coating it using SAM.•The effects of the immersion time and the temperature were investigated.•We suggest mechanism of adsorption and releasing inhibitor from the metal surface.•The result shows that the inhibition efficiency reaches 92.32%. Corrosion inhibition by red pepper seed oil (capsicol) on 304 stainless steel (SS) was studied in 1M HCl solutions. The oil was extracted from the seed of the red pepper (Capsicum annuum L.), which was cultivated in East Java, Indonesia. Electrochemical and optical microscopy techniques were used to observe the performance of the corrosion-inhibition process. The inhibition efficiency reached 92.32% for an immersion time in capsicol of 30min at room temperature and decreased with temperature. This inhibition behavior by capsicol was also justified by comparing the pictures of the samples with and without the inhibitor after corroding for one week.