The aggregation rate is limited by physical interactions, is discussed. The influences of pH and phosphate The aggregation kinetics of sodium deoxycholate in aqueous solution has been studied at pH values close to neutrality. An induction time is observed and taken as inversely proportional to the rate constant for the aggregation of two small aggregates to form a larger one but one that is smaller than a critical size. When the critical size is reached, the length of the polymer-like structure allows the entanglement of the aggregates, accounting for the gel behavior of the solution. After the induction time, it is observed that the weight average aggregation number increases linearly with time for more than 50% of the aggregation. This is analyzed through the Smoluchowski equation in its simplest form. The influence of the temperature on the kinetics suggests the existence of a kinetic-thermodynamic relationship. It is deduced that the and the role of hydrogen bond in the aggregation rate concentration are also studied and discussed.