Cardanol, on catalytic hydrogenation, gives 3-pentadecylphenol (3-PDP), which is used in industry as a plasticizer for cellulose products and fixative for perfumes. It is also used for making surface active agents, azo-pigments, dyes, pale coloured resins, etc. Catalytic hydrogenation of cardanol has been studied using commercially available catalysts to determine the optimum conditions for the preparation of 3-pentadecylphenol. The purity of the product was determined by TLC and NMR techniques. 3-Pentadecylphenol with m. p. 51. 0 C and iodine value (RK) 256. 5 is obtained under the following optimum conditions: temperature, 150 C; pressure, 150 psig; amount of the catalyst, 0. 75% on the weight of cardanol; and hydrogenation period, 2 hr.