A dissolvable composition is disclosed. The composition includes a first material (e.g., an anode), a second material (e.g., a cathode), and a third material (electrolytic material). The third material is reactive with water to form an electrolyte. The first material and the second material are electrochemically different such that the first material and the second material are capable of galvanic reaction in the presence of water and electrolytes. Also disclosed are tools or other apparatus made from the composition, as well as processes, systems, and apparatus for making and using such compositions, tools, and other apparatus.