A series of cobalt doped nickel ferrite with composition of Ni1-XCoXFe2O4 with x ranges from to (in steps of ) was prepared by using co-precipitation method and subsequently sintered, annealed at 6000C for 3h. The influence of the Co content on the crystal lattice parameter, the stretching vibration and the magnetization of specimens were subsequently studied. XRD and FTIR were used to investigate structure and composition variations of the samples. All samples were found to have a cubic spinel structure. .