Autoclaves of late, have become important tools in the aerospace industry to manufacture / cure fibre reinforced composite components. In order to obtain a good quality component it is very necessary that the component be cured strictly in accordance with the prescribed cure cycle. The temperature, pressure and vacuum are three critical parameters which vary in the course of a cure cycle. Modern autoclaves have the provision to pressurize using Nitrogen apart from air so that inert atmospheres can be obtained when required. The pressurization system must be able to cater to the fast pressurization and depressurization rates required by the cure cycle. Like wise, the . heating and cooling system must be adequate to respond to the prescribed heating and cooling rates. Also, the vacuum system which is a closed loop system must be capable of meeting the cure cycle requirments. All the above systems are computer controlled. This report provides a brief description of the design aspects of the various systems of the autoclave.