In this study, a nanoscale sensor on a metal-insulator-metal (MIM) platform was studied numerically to investigate its hydrogen detection potential. The plasmonic MIM structure, which consists of an air micro-ring resonator (MRR) and a palladium (Pd) disk, is used for this purpose. The results of the numerical study show that when the optimum geometric design parameters are employed, a sensitivity as high as 267 pm/(v/v-% hydrogen) can be obtained. In addition, a response time of 172.125 s could be achieved, which is calculated according to the second law of Fick. The result of the study can lead future studies to design fast and high-precision hydrogen gas sensors on a nano-scale base.