In the title compound, C(10)H(9)N(3)O(3), the benzene ring is almost coplanar with the heterocyclic ring, making a dihedral angle of 11.3 (1)°. The plane of the carboxyl group is rotated by 8.4 (2)° with respect to the 1,2,4-oxadiazole ring plane. The aliphatic chain exhibits an extended conformation. In the crystal, mol-ecules are liked through inter-molecular O-H⋯N bonds, forming a chain structure along the c axis.