The corrosion rates in the presence of Hexa Propylene Glycol Cyclotriphosphazene (HPGCP) ascarbon steel corrosion inhibitor in 3 % NaCl has been investigated in temperature ranging from 298 to 328 K using weight loss measurements and electrochemical polarisation. The inhibition efficiency of HPGCP decreases with the rise of temperature. HPGCP is adsorbed on the steel surface according to Langmuir isotherm model. Both kinetic parameters (activation energy, enthalpy of activation and entropy of activation) and thermodynamics of adsorption (enthalpy of adsorption, entropy of adsorption and Gibbs free energy) were calculated and discussed. The fundamental thermodynamic functions were used to obtain important information about HPGCP inhibitory behavior.