Intermetallic phases and mixtures of intermetallic phases in the Sn-Mn-C ternary system were prepared by mechanical alloying. The reaction of lithium with these phases was studied using in situ X-ray diffraction and electrochemical methods. Studies concentrated on Sn2Mn, SnMn1.77, SnMn3, and SnMn3C. Nanoscale two-phase mixtures of Sn2Mn/SnMn1.77 and Sn2Mn/SnMn3C were also prepared and studied. When Sn2Mn is mixed with sufficient amounts of a second phase, electrodes capable of delivering over 200 mAh/g for more than 50 cycles can be prepared. Grain boundary tin atoms in nanostructured SnMn3C appear to be able to react reversibly with lithium for hundreds of cycles.