Density functional theory (DFT) method was performed to investigate the adsorption behavior of Rh-doped MoSe2 (Rh-MoSe2) monolayer towards H-2 and C2H2 in transformer oil. Density of state, electron localization function and charge density difference were analyzed to study the electronic behavior of Rh-MoSe2 monolayer upon gas adsorption. Meanwhile, the desorption performance analysis was conducted as well to determine the recyclability of our proposed material for sensing application. It is found that, Rh-MoSe2 monolayer behaves good adsorption and desorption performances upon H-2 molecule, which allows its exploration of H-2 sensor at room temperature. On the other hand, the inferior desorption behavior of Rh-MoSe2 monolayer with poor reversibility upon C2H2 molecule (1.65 x 10(15 )s at 298 K) make it one-off operation for C2H2 detection. However, its potential adsorbent application could be awaken to scavenge C2H2 impurity from transformer oil, which offers another prospective alternative to guarantee the stable operation of transformers. At room temperature, it is found that Rh-MoSe2 monolayer has superior response for H-2 and C2H2 detection provided the sensitivity of - 98.56% and - 99.63%, respectively. Moreover, frontier molecular orbital theory is employed to confirm the sensing mechanism of Rh-MoSe2 monolayer upon two gases, according to the increased energy gaps that indicate the reduced conductivity after gas adsorption. From this aspect, our theoretical calculations in this paper would be beneficial to provide a novel insight into the application of Rh-MoSe2 monolayer in engineering research.