Several materials issues and challenges exist for the use of hydrogen in energy applications and form the basis for hydrogen R&D in Canada. Many of the challenges are similar for both domestic and defence applications, but there are several unique end-use requirements. In military applications the overall system should have highest energy density possible and reliably deliver for the duration of the required mission. For high energy density, this means the more hydrogen per unit weight and/or volume that can be generated, stored or carried, the better. Safety of carrying hydrogen on or near soldier is an important issue. In the military, both reversible hydrogen storage versus single use, have a place in some military applications with the classic example being metal hydrides versus chemical hydrides. Understanding and developing alternative hydrogen producing fuels with high energy densities is an important R&D effort.