In this investigation, attempts have been made to study the inhibitive effect of triethylene tetramine (TETA) and hexamethylene tetramme (HTMA) for mild steel in 1 M hydrochloric acid in the concentration ranged of 10(-6) to 10(-2) M by weight loss, DC polarization methods and AC impedance spectroscopy. Results indicate that the addition of tetramines to the acid reduce the rate of metal attack. For both the amines, inhibition efficiency increases with the concentration of amine. The inhibition efficiency of the hexamethylene tetramine is less when compared to that of triethylene tetramine. (C) 2004 Elsevier B.V. All rights reserved.