Tin-bismuth (Sn-xBi) deposits, one of the typical lead-free solder materials, with variable compositions were electroplated from the CN--free solutions under a direct-current (dc) plating mode. The prediction and control of Sn-xBi composition can be achieved by using the fractional factorial design (FFD) coupled with the response surface methodology (RSM). The pH of plating baths, the current density of deposition, and the total concentration of metallic ions (i.e., Sn4++Bi3+) were found to be the key factors influencing the composition of Sn-xBi deposits. The success in co-depositing the eutectic Sn-57Bi alloy was supported by the eutectic point of 139 degrees C determined from the differential thermal analysis (DTA). The surface morphology and crystalline structure of various Sn-xBi deposits before and after reflowing in N-2 at 260 degrees C for 10 min were examined by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. These textural results reveal that the binary Sn-xBi deposits prepared in this work belong to heterogeneous alloys. Complete melting of Sn-xBi deposits with x between 49 and 63 can be achieved by the reflowing application at 260 degrees C for 10 min in the inert atmosphere.