Density functional theory calculations have been used to evaluate the geometries and energetics of interactions between a number of uranyl complexes and hydrogen bond donor groups. The results reveal that although traditional hydrogen bond donors are repelled by the oxo group in the [UO2(OH2)(5)](2+) species, they are attracted to the oxo groups in [UO2(OH2)(2)(NO3)(2)](0), [UO2(NO3)(3)](-), and [UO2Cl4](2-) species. Hydrogen bond strength depends on the equatorial ligation and can exceed 15 kcal mol(-1). The results also reveal the existence of directionality at the uranyl oxo acceptor, with a weak preference for linear U=O-H angles.