The effect of metal ion doping on electronic band structure and charge carriers' effective mass of Ta2O5 were studied using hybrid functionals in density functional theory. PBE0 hybrid functional proved to be very efficient in predicting the band structure with less than 5% error compared to experimental data. The bandgap decreases monotonically as the percentage of the dopant increases. Furthermore, the indirect bandgap behavior of Ta2O5 was found to initially increase with doping before it decreases again to its original value of pristine Ta2O5. We found that high doping content or even mixing with another metal is required in order to modify the band structure of Ta2O5. The effect of doping on the crystal structure was also studied. XRD measurements show that the crystal lattice tends to expand upon doping with metals with larger atomic radius than Ta and this effect is more pronounced as the dopant content increases.