Abstract: In this paper, thermodynamic analysis of pentane isomerization to isopentane was carried out in detail. Thermodynamic data, including standard molar enthalpy change, standard molar Gibbs free energy change and standard equilibrium constant at various temperatures were calculated. The effects of temperature, pressure, and molar ratio of hydrogen to hydrocarbon (H2/HC) on the isomerization rate of pentane were discussed. It is found that the isomerization of pentane is an exothermic reaction, lower temperature favors the proceeding of reaction and the cracking reactions of pentane are suppressed as well. Hydrogen partial pressure has significant effect on the conversion and selectivity of pentane isomerization, overhigh hydrogen partial pressure leads to decrease of pentane conversion. The experimental study on isomerization of pentane to isopentane was conducted in a fixed-bed reactor, using RISO C5/C6 paraffin isomerization catalyst developed by Research Institute of Petroleum Processing. Results show that the experimental data agree well with the thermodynamic calculation results. However, reaction temperature, pressure and H2/HC ratio are the main factors affecting the isomerization process, it is essential to optimize these parameters for an optimum utilization of catalyst.