Onion (Allium cepa L.) belongs to family Alliaceae, a native of central Asia is one of the oldest vegetable crops known to mankind and consumed worldwide. It is commercial nutritious bulb crop and ranks second only to tomato in their importance as vegetable in the tropics and with variety of potential uses. The present study was, therefore, undertaken with the following specific objectives: 1. To study effect of pretreatments on dehydration of white onion. 2. To compare the various methods of dehydration of white onion. 3. To find out suitable pretreatment and method of dehydration for white onion.