Future manned spacecraft will require thermal management systems that effectively and safely control the temperature in inhabited modules. Interface heat exchangers will be required that isolate the heat transfer fluid in the spacecraft thermal bus from the circulating water used to cool inhabited modules. We propose to develop an innovative heat exchanger that provides two completely independent physical barriers between the two fluids in the interface heat exchanger. This isolated flow path heat exchanger incorporates two key innovations: (1) an innovative and simple core construction that separates the two fluids while providing a large heat transfer area, and (2) innovative materials that enable efficient heat transfer between the two fluid streams. The proposed heat exchanger is lightweight, efficient, and simple to fabricate. Phase I proves the feasibility of our approach through laboratory demonstrations of the key technologies. In Phase II we will design, build, and demonstrate performance of a full-scale interface heat exchanger sized for a specific NASA application.