A series of Pt catalysts supported on H beta zeolite ion-exchanged with Cr(III) were prepared, characterized by ICP, XRD, BET, NH3-TPD, H-2-TPR and H-2-chemisorption techniques, and evaluated in hydroisomerization of n-heptane with an atmospheric fixed-bed flow reactor. Pt catalyst supported on H beta zeolite exhibits both lower selectivity to isomerized products and lower conversion of n-heptane than the counterparts supported on Cr(III)-exchanged H beta zeolite. The optimal composition for Cr-bearing catalysts is 0.4 wt.% of Pt loading and 0.7 wt.% of Cr loading. This catalyst proves to be highly efficient in the hydroisomerization of n-heptane, giving a very high selectivity to isomerized products: 95.4% coupled with a high conversion of n-heptane: 72.1%. The substantial promotion effect of ion-exchanged Cr(III) species is discussed in relation to catalyst physicochemical properties. (C) 2009 Elsevier B.V. All rights reserved.