This paper describes a novel coaxial cable Fabry-Perot resonator for sensing applications. The sensor is fabricated by creating two highly reflective mirrors in a coaxial cable. The device physics was discussed. The temperature response of the sensor was tested. The temperature measurement is achieved by monitoring the frequency shift of the reflection and transmission spectra as the temperature is increased linearly in steps of 5 °C from 35 °C to 80 °C. This sensor exhibited high temperature sensitivity and measurement resolution. The high quality factor of this sensor leads to high measurement resolution. Highest Q factor of 133 was recorded. It has been derived that the Q factor decreases as the frequency increases.