The performance of electrostatic precipitator (ESP) is significantly affected by its complex flow distribution arising as a result of its complex inside geometry. In the present study the gas flow through an ESP used at a local thermal power plant is modeled numerically using computational fluid dynamics (CFD) technique to gain an insight into the flow behavior inside the ESP. CFD code FLUENT is used to carry out the computations. Numerical calculations for the gas flow are carried out by solving the Reynolds averaged Navier–Stokes equations coupled with the k–e turbulence model equations. The results of the simulation are discussed and compared with on-site measured data supplied by the power plant. The predicted results show a reasonable agreement with the measured data. The model developed is a novel tool for the thermal power plant to predict the effect of possible modifications made to the ESP design on the flow pattern.