A convenient, inexpensive, and efficient synthesis of 3-phenylpropionic acids (1a-1f) by reacting benzaldehyde (2a-2f) and malonic acid in acetic acid and piperidine into cinnamic acid (3a-3f) in 77 to 89% followed by its reduction with PdCl2 in the biphase of formic acid and aqueous sodium hydroxide is reported under microwave irradiation which utilizes short reaction time ranging 5 to 7 min to provide 1a-1f in moderate to high yield (69-86%) depending upon methoxy, methylenedioxy, and hydroxy groups present at the phenyl ring.