Uniformly dispersed particles of CdCO3 were prepared by homogeneous precipitation from aqueous solutions of cadmium sulphate and urea at the elevated temperatures. These particles were then employed as cores for coating with 2CoCO(3). Co(OH)(2). H2O from cobalt nitrate and urea solutions at 85 degrees C. In the absence of cores, when heated under similar conditions, the coating solutions produced nearly uniform particles of 2CoCO(3). Co(OH)(2). H2O. On calcination at 700 degrees C, the core [CdCO3], coated [CdCO3/2CoCO(3). 3Co(OH)(2)], and coating precursor [2CoCO(3). Co(OH)(2). H2O] particles transformed into CdO, CdO/Co3O4, and Co3O4, respectively. No sintering occurred during calcination and the particles preserved their morphological features to a significant extent.