A process for producing an a-arylalkanoic acid ester represented by the general formula
wherein Ar represents an aryl group which may optionally be substituted, and R' and R 2 , independently from each other, represents a lower alkyl group, which comprises reacting a Grignard reagent prepared from an aryl halide of the general formula
wherein Ar is as defined above and X 1 represents a halogen atom, and magnesium, with an a-haloalkanoic acid ester of the general formula
wherein R' and R 2 are as defined above, and X 2 represents a halogen atom, said reaction of the Grignard reagent with the a-haloalkanoic acid ester of general formula (III) being carried out in the presence of a nickel compound.