The inhibition efficiency of Cyperus Rotundus extract on the corrosion of oil and gas pipeline steel in 1.0N Hydrochloric acid in various concentrations with temperature was investigated by mass loss measurement and electrochemical techniques. The observed results indicate that the inhibition efficiency is increased with increase of inhibitor concentration but decreases with rise in temperature. The inhibitor obeys Langmuir adsorption isotherm. Thermodynamic parameters (Viz: Ea, Qads, ΔGads, ΔH and ΔS) revealed the adsorption of the inhibitor is physisorption, exothermic and spontaneous. The inhibition efficiency was found to be 81.95%and 82.01% by impedance and polarization studies respectively. The study also showed that CR extract functioned as a mixed-type corrosion inhibitor in acidic environment.