In this study, rapidly solidified Co-Sn-Ti and Co-Sn-Si alloys were investigated as candidate cathodic materials for lithium-ion batteries. (Co0.5Sn0.5)1-xTix (x=0.1, 0.2, 0.3, 0.4) and (Co0.5Sn0.5)0.9Si0.1 alloys were produced by Ar arc-melting. These alloys were further rapidly solidified into ribbons by the single-roll melt-spinning method. Constituent phases in the ribbons were identified by XRD, indicating that all of the alloys were composed of crystalline multi-phases with no amorphous phase. The microstructure of the ribbons was observed by SEM and TEM, and the chemical composition of constituent phases was analyzed by TEM-EDS. It is found from the SEM and TEM observations that the grain size of the constituent phases ranged from tens to hundreds nanometers due to the rapid solidification effect.