Reactor vessels with transmissive surfaces for producing hydrogen-based fuels and structural elements, and associated systems and methods. A chemical reactor in accordance with a particular embodiment includes a reactor vessel having a reaction zone, a hydrogen donor source coupled in fluid communication with the reaction zone, and a steam source coupled in fluid communication with the reaction zone. The reactor further includes a transmissive surface at the reaction zone, with the transmissive surface being transmissive to a reactant entering the reaction zone and/or radiant energy entering the reaction zone.