Oxygen isotope data are presented for silicate minerals separated from a variety of rock types from the 130 Ma Okenyenya igneous complex of northwestern Namibia. These rock types include a tholeiitic suite ranging from olivine gabbro to quartz monzodiorite and syenite, and an alkaline suite including gabbro, syenite, nepheline syenite, and essexite. In general, the difference in δ18O values between coexisting feldspar, pyroxene, and biotite are consistent with equilibrium at high temperatures and preclude significant interaction with magmatic or external fluids.