Antioxidants can protect normal cells from reactive oxygen species as a protective agent. Therefore, it is important to know radiation attenuation properties of antioxidants. In the present study, nine different types of antioxidant samples were investigated using Monte Carlo simulation method. MCNPX general-purpose Monte Carlo code (version 2.6.0) was utilized to investigate the attenuation parameters of antioxidant samples such as Rosmarinic acid, Butylhydroxyanisole, Butylhydroxytoluene, Morin, Piperonyl butoxide, Ascorbyl Palmitate, Citric acid, Malic acid, and Nordihydroguaiaretic acid. The mass attenuation coefficients (mu/p) values have been calculated against photon energies of 0.122, 0.356, 0.511, 0.662, 1.173 and 1.33 MeV. From these values, the effective atomic number (Zell), mean free path (MFP) and half value layer (HVL) have been calculated and compared with XCOM data. The results obtained by the MCNPX Monte Carlo code were close to those of standard XCOM data. The obtained results showed that the attenuation of photons in antioxidant samples increased with decreasing energy. Z(eff) values for the selected antioxidants molecules varied between 3.75-4.787. It is also found that malic acid and citric acid have smaller HVL values comparing with rest of antioxidants examined. It can be concluded that, modeled and validated standard MCNPX geometry could be useful to the scientific community for similar future radiation-attenuation studies using different types of biological materials and biological systems.