The known van der Waals and Berthelot equations of state do-not precisely describe the thermodynamic properties of fluids. To improve its accuracy, the attractive term of the van der Waals equation of state has been modified in six different ways. These generalized equations of state have been employed to determine the spinodal (thermodynamic stability boundary) and the thermodynamic limit of superheat of liquid lead. The equations of state are rewritten in reduced form, from which follows the law of corresponding states. The appropriate modification of the attractive term of the equation of state yielding the value of thermodynamic limit of superheat agreeing with the experimental value for lead has been established. It has been established that liquid lead can be superheated, under rapid heating, up to a temperature 4565 K. That is, liquid lead can be superheated to 2544 K above the normal boiling temperature. At the thermodynamic limit of superheat, the volume of the liquid lead is 4.0095 × 10-5 m3 mol-1. This fact is to be taken into account when liquid lead is subjected to rapid heating.