The process of Delta T driven contact melting of solid phase change material (PCM) around a horizontal cylinder is analyzed in this paper. Considering the difference of the normal angle between the horizontal cylinder surface and the solid-liquid interface of the melting PCM, the fundamental equations of the contact melting process are derived with film theory. The new thickness of the boundary layer, the variation law of the normal angle of the solid-liquid interface, the pressure distribution inside the boundary layer and the melting rate of the moving heat source are also obtained. The effect factors on the melting are discussed and some useful conclusions and advices are given. (C) 2007 Elsevier Ltd. All rights reserved.