Composite Overwrapped Pressure Vessels (COPVs) are used for storing pressurized gases on board spacecraft when mass saving is a key requirement. All future mass critical space applications will be designed to use COPVs to minimize vehicle mass. Saving mass is critical for facilitating deep space travel in which a series of space depots will be implemented as a means of providing fuel along the journey. These depots will require a means for long-term storage of fuel and other resources that can be placed in the appropriate locations ahead of time. Metal Matrix Composite (MMC) materials offer tremendous potential for lightweight propellant and pressurant tankage. Touchstone teamed with Carleton Technologies Inc. (a subsidiary of Cobham) to demonstrate feasibility of this technology in Phase I. A COPV with Al MMC liner was designed and a demonstration liner was produced. The proposed Phase II effort will address key technical risk items identified in Phase I, optimize the liner design and process, and extend the Technology Readiness Level to 5 by completing validation testing on a full-scale COPV demonstration article.