A composition useful for the fueling and refueling of electrochemical devices is described. The composition comprises an ion-conducting medium such as an electrolyte, and catalyst nanoparticles. Unlike traditional electrodes, such as those typically used in electrolyzers and fuel cells, the inventive composition may be quickly drained from the device and refilled to maintain maximum cell performance. In addition, the electro-catalytic charging composition can be stored as a solid for safe handling; for example in a portable cartridge.