Three reducing sugars, namely glucose, fructose and maltose were tested as inhibitors of C-steel corrosion in alkaline solution. Their inhibition efficiencies were measured using weight loss and potentiostatic polarization techniques. It was found that the addition of any of the three sugars reduce the corrosion rate of C-steel. The inhibition efficiency decreases according to the order; glucose > fructose > maltose. The adsorption of glucose molecules on the C-steel surface follows Langmuir adsorption isotherm, whereas the adsorption of fructose or maltose do not obey it. It was found also that the three sugars act as anodic inhibitors where their oxidation reactions interfere with the anodic corrosion reaction of C-steel. The inhibitive effects of the tested sugars were discussed in view of their relative reducing power. Furthermore, uv-visible spectra were recorded for the test solutions after the completion of weight loss experiments. The recorded spectra suggested a formation of metal-sugar complexes.