This paper studies the stability and transient response of electrostatically excited microbeam interacting with bounded compressible fluid. At first, employing Fourier-Bessel series, the related eigenvalue problem of the coupled system is solved. Investigating the change in the free vibration properties of the system, a parametric study is done, accounting for changing physical properties and geometric dimensions of the bounded fluid. Then, considering the step response of the coupled system, pull-in time and voltage and also attraction zones of the microbeam are derived. It is shown that, beside the electrical property of the contained fluid, its inertial property could also change the transient response significantly. Fluid added mass by increasing the period of the free vibration response in stable condition also changes the pull-in time. In addition, it is found that the attraction zones of stable fixed points vary for different contained fluids that could change the sensitivity of the microbeam to uncertainty in the initial condition.