Isomerization of light paraffin to ranched ones is a way to improve octane number of gasoline. Bifunctional catalysts containing Pt supported on zeolite have been studied widely because the light alkanes can be adsorbed on both metal and zeolite acidic sites. Pt active sites are also necessary for hydrogen in the hydroisomerization reaction. This work studied isomerization of n-hexane in a plug flow reactor on Pt/HY and a mixture between Pt/NaY and Pt/HY (ratio 1:3) to understand the influence of zeolite acidity. Zeolite Y was synthesized with rice husk silica. The catalysts were prepared by incipient wetness impregnation and characterized by XRD, nitrogen and ammonia adsorption-desorption. The catalytic testing was conducted at 300 ºC and 450 ºC using hydrogen as a reactant and carrier. At 300 ºC the selectivity were similar on both catalysts, with the methylpentanes (MP) and dimethylbutane (DMB) as main and primary products and the distribution of isomerization products included 2-MP, 3-MP, 2,2-DMB and 2,3-DMB. At 450 ºC, the 1Pt/HY gave higher cracking products including ethane, propane and butane. The isomerization products were similar products to that at 300 ºC but with higher yields. The mixture Pt/NaY: Pt/HY gave a higher selectivity for n-hexane isomerization at high temperature than Pt/HY indicating that an addition of NaY is necessary for isomerization.