Microstrip transmission lines in the form of an open-ended half wavelength resonator were fabricated on YBa2Cu3Ox thin films deposited on MgO and LaAlO3 substrates using MOCVD. The effects of the microstructure on the performance of the resonator were investigated. C-axis normal YBa2Cu3Ox thin films deposited on LaAlO3 substrate showed a higher quality factor and a lower surface resistance than that on MgO. The c-axis normal film showed a lower surface resistance than a,b-axis normal films. The lowest surface resistance of 22 mOMEGA was obtained for the c-axis normal film on LaAlO3 Substrate in this study.