The kinetics of the spinodal decomposition of the volume phase transition of an N-isopropylacrylamide gel is studied using a turbidity technique. Three stages were identified : the early stage, the transition stage, and the frozen stage. The early stage can be explained by Cahn-Hilliard-Cook’s theory. In the transition stage, the cascading network segment association process causes the turbidity to increase faster than the early stage. The transition stage is characterized by its turbidity growth peak. The final stage, the frozen stage, is characterized by the high turbidity and vanishing turbidity growth rate. In this stage, the spatial concentration variation is frozen and the system enters a semistable state.