A new method has been employed to measure the diffusivity of carbon in alpha iron, The method involves the measurement of ionic current of a carbon concentration cell which employs an iron cylinder as the anode. The design of the cell is such that when a constant external potential is applied, the ionic current is determined by the concentration polarization of carbon in the two electrodes. From the values of ionic current, the diffusivity of carbon (D-c) is calculated by the application of Fick’s law. The results in the temperature range 854-975 K have been fitted by regression analysis to obtain the expression : D-c = 2.448 x 10(-5) exp(-102900.7/RT) with D-c in m(2) s(-1) and R in JK(-1) mol(-1). The results agree well with data in the literature.