Development of a superelastic material with higher stiffness and plateau stresses than binary Nitinol is of interest to the medical device industry because it might allow for smaller, less intrusive devices without compromising the materials characteristics. Ternary NiTiCo alloys in wire form have already been introduced into the market and found very high interest from many guidewire manufacturers. This paper studies the effect of cobalt (Co) alloying additions on the stiffness and plateau stresses of a superelastic nickel titanium alloy. In addition, the general mechanical properties and manufacturability of the alloy are compared to standard binary Nitinol. Generic stent like forms are laser cut, processed, and tested along-side similarly manufactured binary Nitinol parts. The results of this study shows that the effect of Co on the properties is significant and Co is an interesting alloying addition that should be considered for future medical devices in applications where higher plateau stresses together with an increased slope of the linear elastic part of the austenite stress strain curve (i.e. Young's Modulus of the Austenite) are of concern. Furthermore, the increased plateau stress could be used to reduce the profile of the stent struts, resulting in a smaller device.