In the design of a capacitive accelerometer, good mechanical sensitivity is desirable. A study of the optimization of flexure geometry in out-of-plane capacitive accelerometer for mechanical sensitivity enhancement is presented in this paper. The movable proof mass is suspended over the stationary electrodes by means of flexures anchored onto the substrate. The smallest possible spring constant of the flexures that will give the desired displacement was determined. Based on the spring constant's value, various combination of flexure length and width were selected and simulated using CAD software. The spring constant and displacement variations with the flexure dimensions at an applied acceleration was observed and analyzed. The modal and harmonic analysis were also simulated to ensure the linearity and the stability of the dominant mode of the device operation. Optimum results of the flexure geometry are presented and discussed.