Fe-based shape memory alloys (Fe-SMA) unique properties have enabled structural engineers to use them innovatively as a pre-stressed reinforcement in concrete. The life span of a reinforced concrete structure is between 50-200 years, and time-dependent deformation (creep) of reinforcement plays vital role in determining the service life of structures. Unlike conventional steel, Fe-SMA shows a pronounced transformation induced creep at room temperature within a short time that might affect its pre-stressing capabilities. In-situ synchrotron creep of Fe-SMA was conducted to understand the rapid creep mechanism. A creep strain of upto 1.84% at 769 MPa was observed within one hour holding at room temperature. A rapid creep is observed for initial few minutes and later the creep strain tends to saturation. Transformation from γ austenite to ε martensite during creep is evident from the diffraction spectra and rapid creep strain is a consequence of fast transformation from γ to ε. Transformation kinetics traced from the phase peak properties provides further insights on creep depending on the grain family.