Catalytic conversions of propylene, propane and n-pentane to aromatic hydrocarbons over gallium-substituted silicalites were studied. Temperature-programmed desorptions(TPD)with ammonia and propylene and intracrystalline effective diffusivity measurements of reactants were carried out to investigate the catalytic properties of gallozeolites for each reaction. The selectivity for aromatic compounds was higher over the gallium-substituted catalysts than over HZSM-5 and the effect of gallium on the selectivity for aromatic compounds was found to be in the order of propane>n-pentane>propylene. It was explained that the higher selectivity for aromatic compounds over gallozeolites might be attributed to great adsorption strengths of olefins and high effective diffusivities of lower hydro-carbons.