To observe the direct effect of molybdenum reinforcement on nuclear radiation shielding properties, a detailed investigation was performed with a group of bismuth borate glasses. Accordingly, glass samples with the nominal compositions (65-x)B2O3 + 20Bi(2)O(3) + 15Na(2)O + xMoO(3): x = 0, 1.5, 3, 4.5, 6 and 7.5 wt% have been synthesized by the solid state conventional method. The samples were named as M0 (x = 0), M1 (x = 1.5), M2 (x = 3), M3 (x = 4.5), M4 (x = 6) and M5 (x = 7.5). Physical characteristics and gamma-photon attenuation properties of (M0-M5) glasses have been investigated via MCNPX simulation code and XCOM program. XRD patterns confirmed that M0-M5 glasses were in amorphous nature. The density of the prepared glasses increased from 4.4104 for M0 glass sample to 5.3012 gm cm(-3), while molar volume decreased from 33.50083 to 28.92114 cm(3) mol(-1). The mass attenuation coefficient (mu(m)) increased with the increment of MoO3 concentration in mol% and followed the order: (M0)mu(m) < (M1)mu(m) < (M2)mu(m) < (M3)mu(m) < (M4)mu(m) < (M5)mu(m) at all photon energies. The mean free path (MFP), half value layer (HVL), and tenth value layer (TVL) for the prepared glasses M0-M5 have the same trend and follow the order: (M5)(MFP, HVL, TVL) < (M4) (MFP, HVL, TVL) < (M3) (MFP, HVL, TVL) < (M2) (MFP, HVL, TVL) < (M1) (MFP, HVL, TVL) < (M1) (MFP, HVL, TVL). The M5 glass sample (with maximum MoO3) achieved highest effective atomic number (Z(eff))and equivalent atomic numbers (Z(eq)) values for all photon energy ranges (low-medium-high). Among all the glass samples, the exposure build-up factor (EBF) and energy absorption build-up factor (EABF) values for M5 glass sample with the highest MoO3 additive are minimum due to the low amount of photons accumulated. These results indicate that M5 glass sample theoretically provides maximum protection for gamma-rays among all the samples.