Single crystals of the linear chain phase Nd2BaNiO5+delta [delta = 0.0
05(1)] have been prepared and the magnetism studied by neutron scatter
ing. The Ni-O chain direction is along the short axis a. Long-range an
tiferromagnetic order sets in below T(N) = 48 K with Nd and Ni moments
parallel to [001]. The Nd2BaNiO5 magnetic cell is doubled along a and
c relative to the chemical unit cell. The magnitude of the moments at
4.9 K is 2.7(2) and 1.2(1)mu(B) for Nd and Ni, respectively.