A theory for the heat transfer to the stagnation point of a hemisphere in a supersonic, high-enthalpy, low-density nitrogen plasma flow was developed. The theory assumed a flow that is frozen with respect to molecular dissociation and relaxing with respect to ionization. The calculations for this partially frozen flow yielded heat-transfer rates that were generally lower than predicted by other theories for both frozen and equilibrium flows. Experimental heat-transfer rates from measurements in a high-enthalpy constricted-arc tunnel agreed with the theoretical value within 10 percent in the mean.