Each mol-ecule of the title compound, C(12)H(18)N(4)O(6), is located on an inversion centre at the mid-point of the central N-N bond. The azo groups C=N of the Schiff base group have an E conformation and the azo groups in the oxime C=N-O groups have a Z conformation. O-H⋯O hydrogen bonds link neighbouring mol-ecules into infinite monolayers perpendicular to the a axis.