Platinum catalysts supported on the mesoporous material synthesized from Y zeolite were applied to synthesis of jet-fuel through n-octadecane hydroupgrading. The mesoporous aluminosolicate, MMZHY was synthesized using Y zeolite as its framework source. The effect of the addition of Mg to Pt/MMZHY catalyst for n-octadecane hydroupgrading was investigated. Catalyst characterization was performed with X-ray diffraction, N2 adsorption, temperature-programmed reduction in hydrogen flow, temperature-programmed desorption of ammonia, and infrared spectroscopy of adsorbed pyridine. The high yield of jet-fuel over the PtMg(2.0)/MMZHY can be attributed not only to the higher dispersion of Pt metal and higher reducibility, but also the higher amount of acid sites and higher strength of acid sites. The selectivity to iso-paraffin in the jet-fuel fraction could be reached above 80% over the optimized PtMg/MMZHY catalyst.