An accurate method for the estimation of iron and manganese by flame atomic absorption spectrometry (FAAS), correcting the inter-elemental interference using an ISO accepted two parameter computational method has been developed for silico-manganese samples. Iron and manganese are determined at 372 and 403.1 nm, respectively, using air-acetylene flame. Interelemental interferences can also be overcome by removing one of the interferant ion by precipitating it with zinc oxide. The evaluation of the methodology has been done using Fe-Mn synthetic mixtures, as well as in certified reference materials. The standard deviation is within 1% in majority of samples studied. Some real samples have also been analysed by the present method and the results compared with titrimetric method of analysis.