In the present work, three new ionic liquids (ILs) were tested as corrosion inhibitors (CIs): 1,2-dimethyl-3-decylimidazole iodide (DDI), N-triethyl methylammonium acetate (TMA) and N-triethyl methylammonium laurate (TML). The tests were carried out in 1.0 M solutions of sulfuric acid (H2SO4) and hydrochloric acid (HCL) in order to inhibit the corrosion of API 5L X-52 steel. The corrosion inhibitors (Cis) were evaluated by Tafel polarization and polarization resistance (R-p). The Tafel polarization results confirmed that DDI, TMA, and TML inhibited the steel corrosion and worked as mixed inhibitors in both corrosive media. In 1.0 M H2SO4, DDI featured the best inhibition efficiency (IE), which ranged from 57 to 95%, whereas TMA in 1.0 M HCl showed the best IE, which was within the 30-70% range. The IE obtained by R-p in 1.0 M H2SO4 was increased as a function of time, while in 1.0 M HCl, it was inversely proportional. The adsorption displayed by DDI, TMA, and TML on the API 5L X52 steel surface was both physical and chemical, which was obtained from different adsorption isotherms.