The various factors affecting energy dispersive X-ray fluorescence determination of iron in solid powder samples were evaluated, to improve the quality of these measurements. Influence of samples/standards preparation and instrumental parameters such as applied voltage to the X-ray tube, tube output current, and duration of acquisition were assessed, and the optimized instrumental parameters were 12 kV, 200 μA, and 200 s, respectively. Linear dynamic range of the spectrometer was found to be 0.0052 to 5.042 g kg −1 . Detection limits of iron in various organic/inorganic samples were found to be 2.5 to 21.9 mg kg −1 . The values obtained during the present method were evaluated with neutron activation analysis.