Cobalt ferrite nanoparticles have been given special interest due to their unique properties, and they are considered an alternative to magnetite nanoparticles due to their chemical inertness to oxidation and unique magnetic characteristics, as magnetite is difficult to resist oxidation, giving rise to additional oxides with a lower magnetization response. The hydrothermal way succeeds in creating cobalt ferrite nanoparticles with highly crystalline nanoparticles at low temperatures, where a crystallization process directly occurs in solutions. This work introduces an eco-friendly hydrothermal method for preparing cobalt ferrite nanoparticles using different bases (NaOH, KOH, and NH4OH). All the products were characterized by XRD and FTIR. The XRD analysis confirms the cubic spinel cobalt ferrite nanoparticles, and their average crystal sizes are 18.7, 18.1, and 12.9 nm for prepared samples using NaOH, KOH, and NH4OH, respectively. The Fourier transform infrared spectra confirm the spinel cobalt ferrite nanoparticles by existence of two bands around 416 and 590 cm-1.