The technique of producing ultrafine powders by vaporization in the high‐intensity arc has been applied to a number of refractory materials, including oxides, carbides, and metals. Particle size ranges of the products obtained lie generally between 100 and 1000Aå. Following a brief resume of the processing technique, a description of particulate characteristics is presented. Such properties as average size, shape, size distribution, sinterability, and chemical reactivity are examined, chiefly by electron microscopy, x‐ray diffraction, sintering tests, and solution rates.