The superelastic thin films (SETF) have an enormous potential for various industrial sectors particularly in biomedical applications. The present work focuses on the influence of oxygen addition on the superelasticity and mechanical performance of Ti-23Nb-0.7Ta-2Zr (TNTZ-(O), at.%) "Gum metal" thin films deposited by DC magnetron sputtering under a mixture atmosphere of oxygen and argon. Many experimental investigations were carried out to evaluate the microstructure modifications, elasticity and hardness of films. Nanoindentation tests showed that adding oxygen led to improve Young's modulus and hardness of TNTZ films. The microstructure analysis showed that preferential orientation and superelasticity of films seem to have a strong dependence on the oxygen ratio injected during the deposition procedure. Increasing oxygen flow rate led to refine the grain size and to densify the compressive residual stress in the TNTZ-O films. The deposition of these innovative superelastic thin films under a considerable quantity of oxygen is recommended and leads to improve their mechanical properties.