1,6-hexanedithiol and 1-hexanethiol monolayer films modified polycrystalline gold electrodes were fabricated by using self assembled monolayer method. Modified electrodes used for electro-catalytic oxidations of iron(II). The calibration curves were obtained in the range of 5.00x10(-8) - 3.85x10(-5) mol.L-1 and 1.00x10(-7) - 2.56x10(-5) mol.L-1 at the Au-HDT and Au-HT, respectively. Detection limit of 1.6x10(-8) mol.L-1 and 3.2x10(-8) mol.L-1 for iron(II) at the Au-HDT and Au-HT, respectively. Validity of the method and applicability of the sensors are successfully tested by determining of Fe(II) in real samples such as drinking water and carob syrup samples.