The corrosion behavior of C38 steel in HCl solution with different concentration of newly synthesized Picolinium-based Ionic liquids, 1-2-(4-Chloro Phenyl) 2-oxoethyl) -4N-Nmethyl) Picolinium bromide (CPOMPB), was investigated by weight loss and electrochemical measurements. Potentiodynamic polarization studies have shown that (CPOMPB) inhibition efficiency was found to increase with increase of the inhibitor concentrations to reach 87 % at 10-3M of (CPOMPB), due to the adsorption of the inhibitor molecules on the metal surface and the adsorption follows Langmuir's adsorption isotherm. EIS spectra exhibit one capacitive loop and confirm the inhibitive ability. To elaborate the mechanism of corrosion inhibition, the kinetic and thermodynamic parameters for Carbon steel corrosion and inhibitor adsorption, respectively were determined and discussed. The effect of temperature on the corrosion behavior with the addition of (CPOMPB), was studied in the temperature range 298-328 K. Results obtained reveal that (CPOMPB) performs excellently as good corrosion inhibitor for C38 steel in 1.0 M HCl. X-ray photoelectron spectroscopic (XPS) analysis of the surface film was applied in order to get better understanding about the relationship between the inhibition efficiency and molecular structure and also to show the presence of the interfacial elements. The addition of potassium iodide (KI) enhanced the inhibition efficiency (E%). Most of the values of the synergism parameter (Sθ) calculated from inhibition efficiency was found to be greater than unity, suggesting that the phenomenon of synergism exists between CPOMPB and iodide ions. The adsorption of CPOMPB alone and in combination with KI followed Langmuir adsorption isotherm. The Optical microscopy (OM) was used for its morphological studies.