PbO-ZnF2-P2O5 glasses doped with different mol% (0.1 to 1.0) of MoO3 have been prepared. Dielectric properties ∊′(ω), tanδ, σAC, of the synthesized samples were calculated from frequency measurements versus temperature. Space charge polarization was used to analyze the temperature and frequency dispersions of dielectric constant ∊′(ω) and dielectric loss tanδ. Quantum mechanical tunneling model was employed to explain the origin of AC conductivity. The AC conductivity exhibited an increasing trend with increasing concentration of MoO3 (up to 0.2 mol%) but the activation energy for conduction decreased. The plots of AC conductivity revealed that the relaxation dynamics depends on MoO3 dopant concentration.