Abstract: Liquid hydrocarbon is prepared with high efficiency from hydrocarbon gas containing C.sub.2 -C.sub.5 paraffinic hydrocarbons and/or C.sub.2 -C.sub.5 olefinic hydrocarbons by bringing the gas into contact with a metallo-silicate catalyst having the following chemical composition in mol %:Si/Me:15-3500OH.sup.- /SiO.sub.2 :0.3-1.0H.sub.2 O/SiO.sub.2 :30-100R/(R+alkali metal):0.05-0.15NaCl/H.sub.2 O:0.01-0.06where R is quaternary alkylammonium cation,alkali metal is Na or K, Me is metal ion of B, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Mo, W, La or Sc,and having the following acidity per g of catalyst:total acid 0.1-4.5 milli-equivalentstrong acid 0.05-2.0 milli-equivalentweak acid 0.05-3.0 milli-equivalent.

Abstract: Low molecular paraffin hydrocarbons can be converted to aromatic hydrocarbons at high yields of 20-30% in the presence of a metallo-silicate catalyst (Si/Me) (wherein atomic ratio of Si/Me is 25-3200 and Me is Al, Ga, Ti, Zr, Ge, La, Mn, Cr, Sc, V, Fe, W, Mo or Ni) modified with 0.25-1.5% by weight of platinum or gallium or a gallium-silicate catalyst (atomic ratio of Si/Ga is 25-3200).Since said catalyst is of high activity and reaction is carried out at low temperatures, reduction of selectivity of the catalyst caused by decomposition of aromatic hydrocarbons produced can be prevented.