A study of the decomposition of ethyl alcohol was made with and without magnesium oxide as a contact agent under the following conditions: low temperatures, long contact time, atmospheric pressure;Studies of the same decomposition were made with and without magnesium oxide as a contact agent in a closed system under high pressure in an 18-8 stainless steel bomb;Because of the different materials used in the construction of the catalyst chambers, a fair comparison of studies cannot be drawn;When the experiment was conducted at atmospheric pressure, the decomposition of alcohol began slightly below 365°C. In the pyrex glass tube containing magnesium oxide. Under high pressure in the presence of magnesium oxide in the 18-8 stainless steel container, the decomposition began at a temperature slightly below 392°C;Between 45 and 55 percent of the alcohol decomposed in the presence of magnesium oxide at atmospheric pressure in the temperature range 440° to 460°C. Under the conditions of high pressure in a closed system, within the same temperature range, 60 to 70 percent of the alcohol decomposed;From the liquid product obtained in the decomposition of alcohol at low pressure, the following substances were identified: undercomposed alcohol, acetaldehyde, acetone, butyraldehyde, methyl n-propyl ketone, butyl alcohol, and 1,3-butadiene. Other substances, seemingly present but not identified, were unsaturated in nature. In the liquid product obtained in the high pressure experiment the only oxygen-containing compounds identified were undecomposed alcohol and acetaldehyde. Experimental facts indicated the presence of saturated as well as unsaturated hydrocarbons;The gaseous product of decomposition obtained at law pressure was predominately hydrogen, 80 to 85 percent. The gaseous product obtained at high pressure was from 40 to 55 percent hydrogen;Time-pressure curves were plotted, showing the course a decomposition of alcohol under high pressure.