Precipitation of noncrystalline aluminum polyphosphate in aqueous medium yields different products, depending on the actual conditions used. Within the P:Al mol ratio = 0.4 - 0.6 in the reaction mixture, strongly hydrated nanosized particles are obtained. Under suitable drying and sampling procedures, these can be observed as individual entities in the transmission electron microscope. Evaporation of an aqueous dispersion yields large aggregates, probably formed by capillary adhesion and surface tension-driven coalescence. Room-temperature compression molding of the powders made from these particles yields translucent monoliths, as expected for superplastic nanosized particles.