This article presents experimental and numerical results for the quench of a gear blank in agitated and stagnant oil. The time history of temperature is determined with a whole-domain optimizer technique inverse solution method. This article offers a procedure to calculate the surface heat transfer on the quenched part by utilizing a straightforward minimization of an appropriate nor m. The article presents 10 variations in setting Icp this inverse problem. The results indicate that dividing the boundary of the gear blank into four zones and assigning a fixed heat transfer coefficient or heat flux to each zone yields an average error of 40 K. This error c an be reduced by either increasing the number of zones or by allowing the heat transfer coefficient or heat flux to vary within the zones. Of these possibilities, variation of heat transfer within the,ones results in a greater reduction of the average error for the required level of computational effort.