Dehydrogenation of citronellol (3,7-dimethyl-6-octene-1-ol) was performed on a copper and alkaline-earth oxide catalyst. CuO/MgO catalysts were prepared by co-precipitation method and were characterized by X-ray diffraction, temperature programmed reduction, and BET surface area. On CuO/MgO catalyst, the main path of reaction is the dehydrogenation of citronellol to citronellal. The dehydrogenation reaction was carried out at atmospheric pressure in a batch reactor at 215 degrees C. Support exhibited varying promoting effects both on the activity and the selectivity to citronellal. Alkaline-earth oxide support has changed surface area of copper oxide catalysts and the phase compositions of copper.