: The shape memory effect is called to the ability to recovering the initial shape of a plastically deformed sample during a thermo-mechanical cycle. Recently, TiNi-based ternary alloys such as TiNiNb and TiNiCu have been increasingly considered. Copper is one of the important alloying elements which affects phase transformation temperatures and reduces hysteresis. On the other hand, it is reported that grain refinement in shape memory alloys could optimize mechanical properties and shape memory behavior. The main purpose of this research is to manufacture and characterize the nanostructured shape memory Ti 50 Ni 45 Cu 5 alloy by cold rolling-annealing process. Several samples of the alloy were produced by a copper-boat vacuum induction melting process. The as-cast samples were homogenized and hot rolled at 900 . The hot rolled samples were then cold rolled up to 70% thickness reduction. Finally, the samples were annealed at 400 about 1 hr. Microstructural and phase evolutions were conducted by optical and electron microscopy, X-ray diffraction and thermal analysis techniques. Mechanical properties and shape memory behaviors were evaluated using tensile, bending and hardness test methods. According to the results of metallography, thermal analysis and x-ray diffraction tests, the samples with the thickness reduction of higher than 50% had a bimodal structure: a matrix with Nano-grains of austenite along with the amorphous structure in shear bands. According to XRD and thermal analysis results, there was no amorphous structure (shear band) in the annealed samples. During the annealing process, recrystallization and crystallization of the amorphous structures occurred together. The amorphous structure in shear bands is supposed to change to the Nano-sized grains. By increasing cold rolling from 20 to 70%, the strength of samples became about twice, the shape recovery percentage increased from 86 to about 100%, and the critical temperatures were decreased about 20 . It is thought that the reason behind these variations is grain refinement. Grain refinement may cause twinning to be the predominant deformation mechanism, enhancing the shape memory effect. Mechanical properties of the Ti 50 Ni 45 Cu 5 alloy were also changed in comparison to the TiNi alloy. The tensile strength of the Ti 50 Ni 45 Cu 5 alloy was increased up to 500 MPa, but hardness was decreased about 35 HV; the critical temperatures were also decreased about 20 . This work clearly showed that thermo-mechanical processing of cold rolling–annealing could improve mechanical and shape memory properties of the Ti 50 Ni 45 Cu 5 alloy. Keywords: TiNiCu; Shape memory effect; Superelasticity; Thermomechanical processing; Nano-grained structure