PurposeThe purpose of this paper is to study electrochemically and by weight loss experiments the effect of P,P′‐Bis (triphenylphosphonio) methyl benzophenone dibromide (TPPMB) on the corrosion inhibition of mild steel in 1.0M HCl solution, which will serve researchers in the field of corrosion.Design/methodology/approachWeight loss measurements were carried out on mild steel specimens in 1.0M HCl and in 1.0M HCl containing various concentrations (2×10⁻⁸M and 2×10⁻⁵M) of the laboratory synthesized TPPMB at temperatures ranging from 303 to 343 K.FindingsTPPMB was found to be a highly efficient inhibitor for mild steel in 1.0M HCl solution, reaching about 98% at the concentration of 2×10⁻⁵M at 303 K, a concentration and temperature considered to be very moderate. The percentage of inhibition in the presence of this inhibitor was decreased with temperature which indicates that physical adsorption was the predominant inhibition mechanism because the quantity of adsorbed inhibitor decreases with increasing temperature.Practical implicationsThis inhibitor could have application in industries, where hydrochloric acid solutions at elevated temperatures are used to remove scale and salts from steel surfaces, such as acid cleaning of tankage and pipeline, and may render dismantling unnecessary.Originality/valueThis paper is intended to be added to the family of phosphonium salt corrosion inhibitors which are highly efficient and can be employed in the area of corrosion prevention and control.