The capability to predict hot spot in solidifying castings is the utmost important issues during parts design. The present study investigated a simple method to predict temperature profile and possible hot spot in solidifying castings based on medial axis interpolation. One of the major features of medial objects is that it is a reduced topology of three-dimensional geometry. Hence, a geometrically complex three-dimensional object can be represented by a combination of medial objects, e.g., 2-3D surfaces and lines. This allows the large amount of geometrical information to be stored with minimal space requirement and the three dimensional object can be manipulated in a two-dimensional space. In this study, we exploit this particular property of medial objects and its possible application to casting. This study proposes a medial axis-based geometric technique that could be used to optimize the insulation padding around the cast-mould interface. Numerical simulation showed that the current geometric method was successful in relocating the hotspot in casting the feeder. © 2013 Asian Network for Scientific Information.