Processing methods are developed for the preparation of a novel multifunctional polymer matrix composite comprised of ultra-high molecular weight polyethylene (UHMWPE) fiber reinforcement and a hydrogen-rich polybenzoxazine matrix. This composite was designed for aerospace applications that require both structural functionality and space radiation shielding. The polybenzoxazine matrix possesses a unique combination of attributes, including: high hydrogen concentration for shielding against galactic cosmic radiation (GCR) and solar energetic particles (SEP); low polymerization temperature; long shelf-life; and low viscosity. The critical processing challenge of achieving composite cure at a low enough temperature to avoid disruption of the crystalline structure of the UHMWPE fibers is overcome. Rheological and thermomechanical properties are investigated using dynamic mechanical analysis. Optimized processing conditions are confirmed through laboratory scale composite molding using a low pressure vacuum bag molding technique. The molding process window is mapped. The effect of post-cure heat treatment on composite properties is investigated. The composite is currently being tested by direct exposure to space radiation on the International Space Station.