In this study, orange peel oil which had been produced by cold press technique was processed. The catalytic reaction of limonene composed of 90-95% of the orange peel oil carried out in different supercritical alcohols, and it was obtained the compound p-cymene mainly. The experiments processed in a packed bed reactor using Pt/Al2O3, Ni/AAl(2)O(3)and Pd/AAl(2)O(3) catalysts in over supercritical conditions of ethanol and 2-propanol. Experiments of reaction time, temperature and pressure scanning were carried out in the ranges of 10-50 s, 245-340 `'C and 6.5-12.5 MPa, respectively. It was observed that Ni/AAl(2)O(3) was ineffective to the conversion of limonene. However, when Pd/AAl(2)O(3) and Pt/AAl(2)O(3) catalysts were used, p-cymene was produced mainly. Especially, when Pd/AAl(2)O(3) catalyst was used, it was detected that limonene converted completely and obtained p-cymene in yield of 80%. Furthermore, p-cymene selectivity of Pd/AAl(2)O(3) was much better compared with Pt/ AAl(2)O(3).