A high 2,6-diethylnaphthalene (2,6-DEN) isomer ratio (62%) and a good 2,6-DEN yield (46 mol%) were obtained by the transethylation of 2-ethylnaphthalene with tetraethylbenzenes over H-Y zeolite catalyst. Steric hindrance and electron density at the substitution sites of naphthalene are two influential factors for excellent selectivity. Silica-alumina catalyst, which cannot be expected to possess shape selectivity, also demonstrated a high 2,6-DEN selectivity.