This work proposes a mathematical function for describing the dependence of mass attenuation coefficients vs. energy for composite materials in the range of 100 keV to 2 MeV. The obtained results show that the proposed function is capable of accurately describing the data with a coefficient of determination of approximately 1 for all investigated materials. Using the proposed mathematical function, the mass attenuation coefficients were interpolated and compared with the results from the Monte Carlo simulation. The results show good agreement when the simulated to interpolated mass attenuation coefficient ratios are in the range from 0.95 to 1.05. Moreover, the values of interpolated mass attenuation coefficients have also been compared with the experimental data in the previous works which indicates that most of these ratios range from 0.9 to 1.1. <br><br><font color="red"><b> This article has been corrected. Link to the correction <u><a href="http://dx.doi.org/10.2298/NTRP1902209E">10.2298/NTRP1902209E</a><u></b></font>