When the hand makes contact with an object, the changes in skin temperature provide information about not only the object's material composition but also its geometry. Consider, for example, the temperature difference felt when touching an aluminum block and a piece of aluminum foil. To study the thermal cues associated with material properties and object thickness, we measured the changes in skin temperature elicited when touching objects with varying material properties and geometries, and compared them to the theoretical predictions obtained from two thermal models, of which one assumes the object having an infinite thickness and the other takes into consideration the actual object thickness. The comparison results indicate that the former model is effective in capturing the rapid temperature changes at the moment of contact and the latter model is better at predicting the total change in skin temperature at the end of contact. These findings provide a knowledge basis for the development of thermal displays for material simulation and automatic object identification systems that identify an object's material composition and thickness based on thermal feedback.