Keywords:M-shell X-ray production cross sections ECPSSR theory Semi-empirical and empirical cross sections a b s t r a c t Theoretical M-shell X-ray production cross sections have been calculated within the ECPSSR model. The semi-empirical cross sections are then deduced by fitting the available experimental data normalized to their corresponding theoretical values for elements with 72 Z 90 by proton in the energy range 0.1e4.0 MeV. Also, an analytical formula has been used to calculate the empirical X-ray production cross sections by direct fitting of the same experimental data, which are found to be universal, both for individual and collective fits.On the other hand, based on the individual fitting which gives the reliable cross sections, we attempt to deduce another new empirical cross sections by assuming that the ratio empirical to ECPSSR of the cross sections is roughly the same for all elements. In addition, our results are presented for selected heavy elements, namely 74 W, 79 Au and 83 Bi, being the most extensively studied. Finally, a comparison is made between the different procedures followed here and the experimental data.