Terbium substituted cobalt ferrite with composition of CoFe2-xTbxO4 nanoparticles (x = 0-0.5) were prepared employing a reverse micelle process. The effect of Tb3+ cations substitution on structural and magnetic properties of cobalt ferrite nanoparticles was investigated. X-ray diffraction and field-emission scanning electron microscopy evaluations demonstrated that single phase spinel ferrites with narrow size distribution were obtained. The particle size was beyond the range of superparamagnetic range. Vibrating sample magnetometer was employed to probe the magnetic properties of the samples. It was found that with an increase in terbium content, the coercive field decreases while the saturation of magnetization increases. The Mössbauer spectroscopy was used to determine the site preference of constitutive elements. It is interesting to find that adding terbium cations could enhanced saturation magnetization of cobalt ferrite and make it as a suitable candidate for recording head.