The corrosion inhibition of some sulfated water soluble natural polymer (carrageenan) compounds on the corrosion of iron in 1M HCl was studied using weight loss and galvanostatic polarization measurements. The percentage inhibition efficiency was found to increase with increasing concentration of inhibitor and with decreasing temperature. The inhibitive action of these compounds was discussed in terms of blocking the electrode surface by adsorption of the molecules. The adsorption process follows a Langmuir adsorption isotherm. The effect of temperature on the rate of corrosion in the absence and presence of these compounds was also, studied. Some activation thermodynamic parameters were calculated.