<prompt> Most effective method of sterilization by heat isHot airBoilingSteamSteam under pressure  <response>: Most effective method of sterilization by heat is by using moist heat steam above atmospheric pressure Autoclave is a classical example. Principle of autoclave- when water boils under pressure, instead of boiling at 100 degrees, it boils at a higher temperature. Hence the steam generated is at higher temperature. 