CdO whisker crystals with micrometre thickness and length of up to 4.5 mm were grown by a simple technology described in previous publications of the authors. The whiskers grow on CdS crystal substrates, previously covered by a thin metal or silicon layer, on annealing in air at atmospheric pressure. The growth initiator used was Ag, Au, Al, Si, Mn, Ni, Pd or Pt. A study was carried out of the effect of impurities on the conditions and efficiency of growth, as well as on the morphology and composition of the whiskers obtained. The small crystals were examined using an optical microscope, a scanning electron microscope, X-ray structural analysis and X-ray microanalysis. The maximum speed of growth obtained with Au was about 1 mm h-1. The whiskers grow with a face-centred cubic lattice. The largest crystals are in the form of a parallelipiped with facets of {100}. Data are obtained which support the vapour-liquid-solid mechanism of crystal growth. The possibility is also shown of growing whiskers on zinc or cadmium plates covered with a thin layer of Cu, Ag, Au or Al by applying the same technology.