Microstructure, precipitation behavior and mechanical property of the supersaturated single-phase Co-based superalloy are investigated in terms of materials processing, and aging condition. Mechanical twining is found to occur at the cold rolling stage. A second phase has been found to precipitate in the cold-rolled alloy with an aging treatment at 1023 K and been revealed to be the Co7Mo6 phase. Hardness values increase with increasing aging time up to 4 h and then decrease with prolonged time of aging. The maximum value of hardness is obtained to be 686 Hv (micro Vickers hardness).