This study investigated emission reductions of polycyclic aromatic hydrocarbons (PAHs), hydrocarbons (HCs), carbon monoxide (CO), carbon dioxide (CO 2 ), particulate matters (PM), and nitrogen oxides (NO x ) from a heavy-duty diesel engine (HDDE) at one low load steady-state condition, 24.5% of the maximum load (40 km/h), using premium diesel fuel (PDF) mixed with various amounts of H 2 /O 2 . Measurements showed that the mixed fuel of HO60 reduced the brake specific fuel consumption (BSFC) most, by an amount of 12.6%, as compared with PDF. Meanwhile, with HO60, the emission of air pollutant was deceased by 32.3% for PAHs, 9.5% for HCs, 7.2% for CO, 4.4% for CO 2 , and 19.3% for PM, but the emission of NO x was increased by 9.9%.