The interface structure of Fe82Ni18/Co (001) Superlattices has been studied with a combination of X-ray and neutron diffraction. The analysis 'reveals highly asymmetric interfaces with total interface widths of 10 +/- 1 ML(monolayers) for Fe82Ni18 on Co and a maximum interface width of 1 ML for Co on Fe82Ni18. In addition it is concluded that there is no detectable long range B2-type chemical order occurring in the interface region. These results are also discussed in the context of previously measured magnetic mornents of the same system. (c) 2006 Elsevier B.V All rights reserved.