Aiming for further improvement of mechanical properties of Co3AlC-based heat resistant alloys, microstructure control was conducted using optical floating zone (OFZ) melting. Unidirectional solidification was performed to align Co3AlC/alpha(Co) two-phase eutectic microstructure. Co3AlC single phase poly-crystal alloys were successfully fabricated far the first time by taking advantage of OFZ. Mechanical properties were evaluated for selected alloys by compression tests at ambient temperature, 1073 K and 1273 K. Excellent elevated temperature strength is achieved in Co3AlC single phase alloys and ductility is sufficiently improved in Co3Al/alpha(Co) two-phase alloys.