Extensive ab initio calculations have been performed to determine the energy, geometry and vibrational frequencies of all stationary points of the N2H2 ground-state potential energy surface. The geometries of trans-, cis- and iso-minima as well as transition states are reported at the MCSCF/aug-cc-pVQZ level, while the relative energetics is established by single point MRCI/aug-cc-pVQZ calculations including the Davidson size-consistency correction. The data is useful for modeling a single-sheeted global potential energy surface for the title system. (c) 2006 Elsevier B.V. All rights reserved.