The introduction of two carboxyl groups into the 4- and 4＇-positions of biphenyl has been achieved by the one-step reaction of biphenyl, carbon tetrachloride and copper powder in aqueous alkali by the use of B-cyclodextrin as catalyst at 78 degrees C under nitrogen of atmospheric pressure, producing 4,4＇-biphenyldicarboxylic acid in 61 mol% yield with 85% selectivity.