Cobalt ferrite (CoFe2O4) nanoparticles were prepared by hydrothermal-chemical route and annealing treatment. It was found that the characteristics of the products depend on annealing temperature and coexistence of the capping molecules in the reactant solutions. The formations of highly monodispersive spherical nanoparticles were confirmed by X-ray diffraction and scanning electron microscope. The functional groups of the magnetic materials were determined by FTIR spectrum. Energy dispersive X-ray results confirmed the ratio of the transition metal atoms in each material according to the nominal stoichiometry. The VSM studies showed that the coercivity and saturation magnetization of CoFe2O4 were found to be maximum for the reported samples. The magnetic hysteresis obtained at room temperature revealed smaller effective magnetic anisotropy. In order to investigate the effect of degree of crystallinity on the mean crystalline size of CoFe2O4 nanocrystals and on the magnetic properties, a serious of CoFe2O4 sample with different degree of crystallinity and size were prepared by varying the synthesis and subsequent calcination temperatures.