A weakly agglomerated 3Y-TZP powder with 100% tetragonal crystal structure and a primary crystallite diameter of 8 nm was prepared by co-precipitation of metal chlorides in an ammonia solution, followed by extensive washing with ethanol, drying and calcining at 550 °C. Powder characteristics as function of thermal treatment are discussed. A copper oxalate precipitation for the preparation of nanocrystalline CuO powders was optimised in order to minimise aggregation and agglomeration. The influence of calcination procedure and synthesis medium on several powder characteristics of the CuO powders were investigated in detail. Oxalate precipitation in ethanol followed by sequential drying and calcination in air at 250 °C in an open tubular furnace with proper air-powder contact area was found to be the optimal procedure for producing nanocrystalline single-phase CuO powder with small aggregates and weak agglomerates. With this optimal procedure a CuO powder with crystallite diameter and BET equivalent particle diameter of respectively 12 and 20 nm was obtained.