One-step synthesis of an octane booster for gasoline and a diesel fuel was performed using glycerol and tert-butyl alcohol (TBA) as raw materials and the solid acid Amberlyst-70 (A-70) as a catalyst. In contrast to the conventional etherification of glycerol with TBA operated at a low temperature resulting in a homogeneous product mixture, our study revealed that the same process at elevated reaction temperatures would automatically separate the products into an organic phase and an aqueous phase. The components of the former consisted of unconverted TBA, isobutylene (IB), 2,2,4-trimethyl-1-pentene, 2,4,4-trimethyl-2-pentene (DIB), 2,2,4,6-pentamethyl-3-heptene, 2,2,6,6-tetramethyl-4-methyleneheptane (TIB), and oxygen-limited hydrocarbons (HCs), which are constituents that are different from the product distribution of the conventional reaction. The latter was composed of water, unconverted TBA, and glycerol. After a simple laboratory distillation of the organic phase product mixture, the distillate obtained by a simple distillation maintained at 225 degrees C in the still could be used as an octane booster for gasoline, while the residue could be adopted as diesel fuel.