Fine particles of cadmium carbonate (CdCO3) were prepared by heating aqueous solutions containing dissolved urea and cadmium sulfate at 85degreesC for 1 h. Effect of the composition of the reactant mixture on the morphology of the precipitated particles was investigated. It was found that the cadmium sulfate content of the reactant mixture significantly affected the shape and size of the precipitated particles. At certain range of reactant mixture composition, cauliflower-shaped uniform particles were obtained. The later particles were coated with basic copper carbonate (Cu-2(OH)(2)CO3) by heating aqueous dispersions, containing CdCO3 particles, copper (II) nitrate, and urea at 85degreesC for various periods of time with constant stirring. The coating process was found sensitive to the experimental conditions and in most of the trials; mixtures of the coated and coating precursor particles were obtained. As such, extensive optimizations were carried out and conditions were established for the production of uniformly coated particles. On calcination at 700degreesC for 1 h, the CdCO3 particles converted into CdO, whereas the coated particles (CdCO3(core)/ Cu-2(OH)(2)CO3(coating) transformed into CdO(core)/ CuO(coating)) without sintering. In the coated particles, the core and coating materials stayed mutually inert during the calcination reaction and independently converted into their respective oxides. All the calcined and uncalcined products were characterized by various physical and chemical methods. (C) 2004 Kluwer Academic Publishers.