While following voltammetric behavior of ultrafine metallic powders, we realized that the results obtained with six metals (Al, Fe, Ni, Cu, Mo, and W) were providing us with material for treating the connection between electroactivity and the state of dispersion of matter. The electroactive species were metallic oxides formed spontaneously on surfaces of the metallic powder particles, and we could follow their electrochemical reactivity in the states of coarse and fine suspensions, colloids, and true solutions. Each state of dispersion can be characterized by a distinctive form of electroactivity, which we illustrated by experimental results with all six metals.