Spinel Cobalt ferrites were synthesized by the co-precipitation method using tetramethyl-, tetraethyl-, and tetrabutyl ammonium hydroxide as precipitating agents. The products were characterized by X-ray diffraction, scanning electron microscopy, atomic absorption spectroscopy, thermogravimetric analysis, and low-temperature nitrogen adsorption measurements. The influence of the length of the carbon chain of the precipitating agent on the progressive development of the spinel structure has been investigated as a function of thermal decomposition temperature. The degree of crystallization depends on the thermal decomposition temperature, and also on the type of precipitating agent used to form the precursor. Tetrabutyl ammonium hydroxide is the weakest base with the highest molecular weight among the three precipitating agents. An increase in the size of the tetraalkyl ammonium cation reduces the crystallite size and lattice parameter of cobalt ferrite spinel. It also appears to reduce the degree of particle aggregation significantly.