In this study copper and stainless steel were explosively welded with different stand-off distance. The effect of stand-off distance on bonding interface was investigated. Experiments showed that, increasing the stand-off distance transform the bonding interface from smooth to wavy shape. However, the excessive stand-off distance leads huge waviness then a smooth bonding in interface. In explosive welding, when a wide stand-off distance is chosen, wave length and it is amplitude increase the extension of grains along the explosion due to the plastic deformation. It is also found that the hardness of regions close to bonding interface was increased because of collision. (C) 2007 Elsevier Ltd. All rights reserved.