Al-Pb-Bi monotectic alloys with three different compositions were melted and solidified under a microgravity environment in the Space Shuttle. The (Pb, Bi) particles were dispersed uniformly in the aluminium matrix, while evident sedimentation was observed in the reference sample processed under 1 G. Slow cooling was also effective to obtain homogeneous microstructure because of the absence of Marangoni force. The alloys were cold-worked into wires and the superconducting properties of the wires were investigated. The distance between (Pb, Si) fibres for the alloys prepared under microgravity was so small that the wires showed complete zero resistance below 9 K due to the proximity effect.