Amorphous tin-cobalt is characterized and its electrochemical behavior compared to that of crystalline tin and tin-cobalt materials. It contains highly uniformed 5 nm diam nanoparticles, which are basically composed of amorphous SnCo and graphitic carbon, with a small amount of titanium. It shows excellent electrochemical behavior in lithium cells. The capacity stabilized at 400 mAh/g for 30 cycles at 0.5 mA/cm(2), in contrast to crystalline tin that rapidly lost capacity after 10-12 deep cycles. (c) 2007 The Electrochemical Society.