Alternating current conduction in BaBi2Nb2O9 (BBN) thin films has been studied over a wide range of temperatures and frequencies. A power law relation was used to explain the frequency dependence of ac conductivity. In the higher frequency region, ac conductivity of the BBN thin films was temperature independent. The activation energy calculated from the Arrhenius plot of ac conductivity was found to be around 0.25 eV. It was attributed to shallow trap controlled space charge conduction in the bulk of the sample. The impedance analysis of the BBN thin films was also performed to gain insight into the microstructure of the films, including the characteristics of the grains, grain boundaries, and film-electrode interface. The response of a single RC combination has been observed for our case. The effect of other components, such as the grain boundary interface and electrode/film interface was negligible. The imaginary component of impedance (Z”) exhibited different peak maxima at different temperatures. A Debye mechanism was found to be appropriate to explain the polarization relaxation in BBN thin films.