Corrosion has always been a costly operational problem in potash solution mining operations. With the aim of reducing operating cost, this work proposed to apply a corrosion inhibitor that is compatible to potash brine environments, less toxic than the base substrate potash, commercially available, and provides sufficiently high corrosion inhibition performance. To identify such inhibitor, three sets of chemicals totaling 19 chemicals were experimentally tested for their inhibition performance on carbon steel (CS 1018) immersed in a saturated potash brine at 85°C, 1 bar and a rotational speed of 1940 rpm. Hexamethylenetetramine (HMTA) satisfied all screening criteria with an inhibition efficiency in the range of 90% and was further evaluated for its inhibition performance not only on CS 1018 but also J55 steel in respect of HMTA concentration (0-4000 ppm), brine temperature (45-85°C) and rotational speed (0-3880 rpm). Results from electrochemical tests showed that J55 corroded more than CS 1018, and both were susceptible to pitting corrosion. HMTA effectively reduced corrosion rates and pitting damage of CS 1018 and J55 with maximum inhibition efficiency of 94.07 ± 0.24% and 99.89 ± 0.02%, respectively. Its inhibition efficiency increased with HMTA concentration and brine temperature but decreased with rotational speed. The optimal HMTA concentration was 1000 ppm. At this concentration, the inhibition efficiency from weight loss studies of HMTA was high in the range of 90.43 ± 0.12% to 94.47 ± 0.32% for CS 1018 and 88.83 ± 0.18% to 95.95 ± 0.41% for J55, and could be maintained over the test period of 21-28 days. HMTA was effective for the metals exposed to liquid- and liquid-vapor phase, but not effective in vapor-phase. HMTA functioned as a mixed-type inhibitor retarding both iron dissolution at anodic sites and reduction reactions at cathodic sites. It protected the metal surface by undergoing chemisorption that obeyed Langmuir and El-Awady adsorption isotherms. The presence of HMTA enhanced capacitor characteristic of CS 1018 and J55, while creating an additional inhibitor film resistance, and significantly enhanced the double layer resistance. The chemisorption of HMTA was spontaneous and endothermic in nature. HMTA was more likely to donate its electrons to metal surface during chemisorption than to accept electrons from the metal.