PURPOSE: To efficiently prepare hydrocarbon rich in arom. components, by contacting hydrocarbon poor in arom. components with a specified crystalline silicate.

CONSTITUTION: A crystalline silicate (ISI-1) having, after baked at 550°C in the air, molar-ratio composition of the formula (wherein M is an alkali or alkaline earth metal; n is the valency of M; 0.3≤p≤3; q≥10) and a specified X-ray diffraction pattern is used as a catalyst. Namely, hydrocarbon poor in arom. components such as a 2W4C gaseous hydrocarbon mixture or liquid hydrocarbon, e.g., a naphtha fraction contg. not more than about 15wt% aromatic components is contacted with said crystalline silicate catalyst. The contact is adequately carried out at a pressure of about atmospheric W50kg/cm2.G, a temp. of about 200W550°C and wt. hourly space velocity of about 0.1W50/hr.