Onion is a commercial crop of our country, belongs to the family Alliaceae. It is used for both internal consumption and foreign exchange. So an experiment was conducted entitled “A study entitled as “Standardization of drying condition for development of onion powder” was conducted at Division of Food Science and Technology at Sher-e- Kashmir University of Agricultural Sciences and Technology, Shalimar. Three cultivars of onion namely Nasik Red, Red Globe, Yellow Globe were selected for pungency evaluation and basedon pyruvic acid content. The selected variety was first subjected to preliminary operations then subjected to osmotic pre-treatment. The treated onion slices were divided in to two lots and thereafter subjected to two dehydration methods viz. hot air drying (600 C and 700 C) and vacuum dehydration were carried out independently. A constant pressure of 50mmHg was maintained during vaccum dehydration. Dehydrated onion slices were then grinded in a grinder to produce powder. The developed onion powder was evaluated for the physio-chemical characteristics such as moisture content (%), water activity (a w ),Dry matter content (%), powder yield (kg/kg of prepared onion slices), true density (g/cm 3 ), bulk density (g/cm 3 ), carr’s index and hausner’s ratio, browning index (420nm), reducing sugars (%), total sugars (%), antioxidant activity (%DPPH Inhibition assay), pungency (µmole/g), phenols (mg GAE/100g) and ascorbic acid (mg/100g).