The effects of Mg and Zn dopants on the catalytic performance of Pt/Al₂O₃ catalyst were investigated for dehydrogenation of perhydrodibenzyltoluene (H18-DBT) as a liquid organic hydrogen carrier. Al₂O₃ supports were modified with Mg and Zn to produce Mg-Al₂O₃ and Zn-Al₂O₃ with a target loading of 3.8 wt.% for dopants. The modified supports were impregnated with chloroplatinic acid solution to produce the catalysts Pt/Al₂O₃, Pt/Mg-Al₂O₃ and Pt/Zn-Al₂O₃ of 0.5 wt.% Pt loading. Thereafter, the catalysts were characterised using inductively coupled plasma- optical emission spectrometry, scanning electron microscopy-energy dispersive X-ray spectroscopy, hydrogen temperature-programmed reduction, carbon-monoxide pulse chemisorption, ammonia temperature-programmed desorption, X-ray diffraction and transmission electron microscopy. The dehydrogenation experiments were performed using a horizontal plug flow reactor system and the catalyst time-on-stream was 22 h. Pt/Mg-Al₂O₃ showed the highest average hydrogen flowrate of 29 nL/h, while an average of 27 nL/h was obtained for both Pt/Al₂O₃ and Pt/Zn-Al₂O₃. This has resulted in a hydrogen yield of 80% for Pt/Mg-Al₂O₃, 71% for Pt/Zn-Al₂O₃ and 73% for Pt/Al₂O₃. In addition, the conversion of H18-DBT ranges from 99% to 92%, Pt 97–90% and 96–90% for Pt/Mg-Al₂O₃, Pt/Zn-Al₂O₃ and Pt/Al₂O₃, respectively. Following the latter catalyst order, the selectivity to dibenzyltoluene (H0-DBT) ranges from 78% to 57%, 75–51% and 71–45%. Therefore, Pt/Mg-Al₂O₃ showed improved catalytic performance towards dehydrogenation of H18-DBT.