Purpose: The purpose of this paper is to adopt both the fragments of imidazole and thiosemicarbazide as reaction centers, to synthesize a water-soluble corrosion inhibitor named as thiosemicarbazide-imidazole derivative (TH-IM). Design/methodology/approach: This paper presents potentiodynamic polarization tests, electrochemical impedance spectroscopy tests and morphology study of metal surface by scanning electron microscope and thermodynamic study. Findings: In the aggressive condition of CO₂ saturated Wt. NaCl solution at 333 K for 72 h with 400 ppm inhibitor dosage, the efficiency of inhibition increases approximately 98 per cent through the method of weight loss. Originality/value: This paper finds a new corrosion inhibitor about TH-IM which has a good solubility in water.