Dual energy x-ray tomography allows the decomposition of CT data into density and composition information in terms of electron density and effective atomic number, respectively. The study proposed a simple iterative algorithm to accurately calculate the distribution of effective atomic number and electron density from a pair of CT images based on linear attenuation coefficients of investigated objects. The proposed method has outstanding features compared with other relevant studies. CT energies can be selected from 50keV to 300keV and materials can be chosen from the range of 6≤Z≤50. The extensive ranges of energy and atomic number do not decline the accuracy of the final results of electron densities and atomic numbers except in few cases.