A new metamagnetic material CoSr2Nd1.1Ce0.9CuO9±d has been synthesised. At 2 K the metamagnetic transition occurs at a field of 0.1 T. We propose to measure the field dependence of the magnetic structure of this material on the WISH diffractometer between 0 - 14 T to determine how the magnetic structure changes with field and whether the Co and/or Cu magnetic sublattices are responsible for the metamagnetic behaviour. A variable temperature neutron diffraction study will also be performed to determine the Co and/or Cu magnetic transition temperatures. Surprisingly CoSr2Nd1.0Ce1.0CuO9±d shows no evidence of a metamagnetic transition in fields up to 7 T. The measurements will be repeated for CoSr2Nd1.0Ce1.0CuO9±d to see if there is any evidence of metamagnetism at higher fields.