In the present work we report design, simulation, fabrication and characterization of thin film bulk acoustic resonator (FBAR). The FBAR has been modeled as a single port device with two terminals. The FBAR has been fabricated using Si-SiO2-Al-ZnO-Al structure. Zinc Oxide (ZnO) films were deposited by RF magnetron sputtering using Ceramic ZnO target in Ar-O 2 (1:1) ambient without external substrate heating. The XRD result confirms the preferred C-axis orientation of the films required for good piezoelectric properties. These ZnO films have been used to fabricate air gap type resonator. A four mask process sequence was used for this purpose. Lift-off process was used to pattern Al top electrode. In order to create the air cavity under the active device area, the bulk Si was etched in 40 % KOH at 80 °C. A specially designed mechanical jig was used to protect the front side of the device during anisotropic etching. Vector network analyzer was used to measure the reflection coefficient (S11: Return Loss) of the device. The resonant frequency of the resonator was measured to be 2.89 GHz as compare to the simulated frequency of 2.85 GHz with a return loss of 14.51 dB. © (2011) Trans Tech Publications, Switzerland.