A process for synthesis of sulfonated, arylated 3-pentadecyl phenol (cross linking catalyst) of formula I starting from Cashew Nut Shell Liquid. Formula I wherein R is benzenesulfonic acid; X is —SO3H, where n is 0 or 1; wherein the process steps comprises hydrogenating cardanol with 5% Pd/C in presence of lower alcoholic solvent at 70° C. under 600 psi hydrogen pressure to obtain 3-pentadecyl phenol; arylating 3-pentadecyl phenol to obtain 3-pentadecyl diphenyl ether; and sulfonating the 3-pentadecyl diphenyl ether to obtain compound of formula I.