A new approach to determine the three micellization parameters for ionic surfactants, the micellization constant K-n, the micelle aggregation number n, and the number of counterions per micelle m, was developed by combination of electric conductivity and either surfactant ion or counterion concentration. The approach employed two slopes of the plots of specific conductivity against surfactant concentration below and above the critical micelle concentration and the mass action model of micelle formation. This approach can be used to determine the other two parameters when the n value is available. This method was applied to the aqueous solution of sodium dodecyl sulfate whose micellizatian parameters have been precisely determined and was found to be quite successful to obtain the three parameters.