In this study, the gamma and neutron attenuation behaviors of pure boron carbide and boron carbide-silicon carbide composites which include three different silicon carbide ratios (20%, 30%, and 40%) by volume were investigated against Cs-137, Co-60 gamma radioisotope sources and Pu-Be neutron source. Transmission technique was used in the experiments to investigate the gamma and neutron attenuation properties of the materials. Linear and mass attenuation coefficients of the samples were determined for 0.662 (Cs-137) and 1.25 MeV (Co-60) energetic gamma rays. In addition the total macroscopic cross-sections (Sigma T) were calculated for the materials against Pu-Be neutron source. Theoretical mass attenuation coefficients were calculated from XCOM computer code. The experimental and theoretical mass attenuation coefficients were compared and evaluated with each other. In addition half value thickness (HVT) calculations were carried out by using linear attenuation coefficients and total macroscopic cross-sections. The results showed that increasing silicon carbide ratio decreases HVTs against Cs-137 and Co-60 gamma radioisotope sources whereas increases HVTs against Pu-Be neutron source. The mass attenuation coefficients were compatible with the theoretical (XCOM) values. Increasing silicon carbide ratio in boron carbide-silicon carbide composites causes higher gamma attenuation and lower neutron attenuation values. (C) 2014 Elsevier Ltd. All rights reserved.