PurposeTo provide a novel synthesized stilbazole derivative as a corrosion inhibitor for researchers in the field of corrosion science.Design/methodology/approachElectrochemical corrosion measurements (tafel plots) were carried out in a 3‐electrode electrochemical cell on the mild steel electrode in 1.0 M HCl and in 1.0 M HCl containing various concentrations (1.0 × 10⁻⁷ M to 1.0 × 10⁻³ M) of the laboratory synthesized trans‐4‐hydroxy‐4'‐stilbazole.FindingsThe percentage inhibition of trans‐4‐hydroxy‐4'‐stilbazole on mild steel in 1 M HCl solution increased with the increase of concentration of that inhibitor. This percentage inhibition steeply increased from 10.11 percent (at 1.0 × 10⁻⁷ M) to 30.34 percent at 1.0 × 10⁻⁶ M. The slope of this increase slightly decreased at the concentration of 1.0 × 10⁻⁵ M to reach 39.61 percent. At higher concentrations, the increase of the percentage inhibition was steeper than the initial part, and reached 97.92 percent at 1.0 × 10⁻³ M.Practical implicationsThis inhibitor could have application in industries, where hydrochloric acid solutions 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 the building block or the nucleus for a new family or group of stilbazole derivatives in electrochemical studies of corrosion inhibitors.