X-ray photoelectron spectroscopy has been used to determine oxygen bonding in a series of xZnO · (1 - x)P2O5 (0.50 ≤ x ≤ 0.67) glasses. Curve fitting of the O1s spectra leads to a quantitative measure of the bridging-to-non-bridging oxygen ratio which is shown to depend on composition according to a simple structural depolymerization model. A third peak, present in the O1s spectra collected from yB2O3 · (1 - y)Zn(PO3)2 (0.00 ≤ y ≤ 0.40) glasses, is due to oxygens which link borate and phosphate tetrahedra. The relative concentrations of P-O-P, P-O-Zn and P-O-B bonds are shown to be in good agreement with a structural model which assumes that borophosphate units (BPO4) form when B2O3 is added to Zn metaphosphate glass.