A variety of formulations was investigated for the fabrication of an appropriate shielding rubber to be used in neutron-gamma mixed fields. Having considered the required mechanical properties together with tungsten as the gamma-ray absorbing element, calculations with MCNPX 2.6 code confirmed that the incorporation of 5 weight percentage (wt%) of boron carbide exhibited the best performance as a thermal neutron absorber.A series of both experimental and simulation results are provided for comparison.