The reactions of acetic acid, propionic acid and/or benzoic acid with ammonia have been carried out over various modified and unmodified HZSM-5 with Si/Al ratios from 30 to 280, H-mordenite, HY, SAPO (40 type) and SiO2-Al2O3 catalysts. The maximum yields of acetonitrile, propionitrile and benzonitrile are 99, 91 and 99% with 99% selectivity over HZSM-5 (30), H-mordenite and SAPO (40 type) catalysts at 400-degrees-C, respectively. An attempt has also been made to develop a methodology to prepare nitriles from carboxylic acids over zeolites.