In the title compound, H(3)O(+)·C(8)H(7)O(8)P(2) (-), the anions form inversion dimmers by way of pairs of O-H⋯O hydrogen bonds involving the phospho-nic functions and via the hydro-nium cation. Further O-H⋯O links involving the hydronium cation play a prominant part in the cohesion of the crystal structure by building bridges between bis-phospho-nate pairs, forming infinite ribbons along the b-axis direction and by cross-linking these ribbons perpendicularly along the a-axis direction, forming an infinite three-dimensional hydrogen-bond network. The benzene ring and the C=O atoms of the furan ring are disordered over two sets of positions of equal occupancy.