The application of 2D materials for detecting dissolved gas molecules is essential for identifying faults in oil-immersed transformers. This study investigates the adsorption properties of ZrCl2 monolayer (ML) and Pd-doped ZrCl2 ML with six gas molecules (CO, CO2, CH4, C2H2, C2H4, C2H6) in transformer oil using the density functional approach. The adsorption behaviour was analysed by calculating and comparing the structures, charge transfer and adsorption energies. Additionally, the chemical interaction and electronic properties of gas molecules on ZrCl2/Pd-ZrCl2 ML are examined through PDOS (projected density of states), band structure, recovery time and work function. The pristine ZrCl2 ML has a weak interaction for all six gas molecules, whereas Pd doping on ZrCl2 ML has considerably increased the adsorption strength for C2H4, CO and C2H2 gases. The results presented in this paper offer a theoretical framework for utilizing Pd-ZrCl2 ML in monitoring transformer performance and gas detection.