Cobalt and cobalt oxide nanocrystals were synthesized on Si substrates from aqueous cobalt nitrate [Co(NO 3 ) 2 $6H 2 O] powder via chemical vapor deposition method. Scanning electron microscope, field emission scanning electron microscope, and transmission electron microscope observations show different morphologies, such as continuous films, nano-bars, nano-dices, and nano-strings, depending on the synthesis temperature. The crystal structure characterization was conducted using Xray diffraction methods. Furthermore, the properties of the samples were characterized using Raman spectroscopic analysis and vibrating sample magnetometer. The morphology change was discussed in terms of synthesis environments and chemical interactions between cobalt, oxygen, and silicon.