Magnetite nanoparticles due to the special specifications have been widely used in medical as well as industrial applications. In such applications, it is important to control morphology and size of the nanoparticles. In this work, magnetite nanoparticles were synthesized via the co-precipitation method. For investigating the effect of various precursors on mean size and morphology of synthesized nano particles, six groups of magnetite precursors were arranged. The magnetite product of each group was characterized by using XRD, SEM, TEM, VSM and the analytical methods. The results have shown the kind of precursors influence on the mean size of the synthesized nanoparticles. The reason for this behavior was explained by the double layer theory. However, kind of precursors did not have a sensible effect on the morphology of the synthesized nanoparticles. (C) 2016 Elsevier B.V. All rights reserved.