2-mercaptobenzimidazole (MBI) has been shown to be an effective inhibitor of carbon-steel corrosion in aqueous solutions of both hydrochloric and sulfuric acid. Here we extend such studies to examine its corrosion inhibition performance in conditions mimicking sweet oilfield brine. More specifically electrochemical measurements have been undertaken from carbon steel immersed in 3.5 wt.% NaCl solution saturated with CO2 (pH ~ 3.9 and dissolved O2 < 40 ppb) both with (1 mM) and without (0 mM) MBI. The impact of both environmental temperature (30°C 55°C and 120°C) and pressure (1 bar and 20 bar) on MBI performance has been explored. Subsequent to immersion substrate characterization has been carried out employing both X-ray diffraction (XRD) and scanning electron microscopy (SEM).In this model sweet oilfield brine it is established that MBI functions as an efficient corrosion inhibitor at solution temperatures of both 30°C and 55°C independent of pressure. XRD and SEM do not indicate the presence of any adhered corrosion product merely evidencing substrate iron along with cementite (Fe3C) for 0 mM MBI solutions. In contrast upon increasing temperature and pressure up to 120°C and 20 bar respectively a corrosion scale of siderite (FeCO3) is concluded to be present both with and without MBI. Furthermore under these conditions MBI no longer inhibits corrosion but rather apparently somewhat enhances the corrosion rate.