Controlled precipitation conditions allow the formation of highly porous, spheroidal aggregates of hydrotalcite. The aggregate structure resembles a house-of-cards, being composed of interconnected thin plates. The aggregate size can vary over a range of about 1 to 60 μm by altering precipitation conditions such as mixing shear, temperature, addition rates and addition order. These materials are low in bulk density and highly absorptive. The aggregate structure is maintained during calcination. The micro and meso-pore size distribution is very similar to conventionally prepared hydrotalcite, but the macroporosity is dominated by the voids between spheroids. The characteristics of these aggregates point to potential applications in areas such as catalysis and separation.