A study about the magnetic viscosity and magnetization reversal in coprecipitated cobalt ferrite was carried out. Measurements of direct current demagnetization reversible Mrev and irreversible Mirr magnetization as well as magnetic viscosity Sn were performed at room temperature along the demagnetization curve for different applied fields Hap(0 > Hap> - 7 kOe). From these data Mrev(Mirr)Hi curves were built. The experimental results show a minimum in the Mrev(Mirr)Hi curves and a nonproportionality between Sn and Xirr; suggesting two different contributions to the reversal magnetization during the demagnetization process.