The experiment was conducted at post harvest technology laboratory, Department of Horticulture, College of Agriculture, Dr. B.S.K. Krishi Vidyapeeth, Dapoli during the year 2009-2010. It consisted of five pretreatments i.e. dipping in 2% alum solution, 2% salt solution, 0.25% KMS solution, 0.1% KMS+2 % CaCl2 solution and control (T5) with three drying methods i.e. sun drying, oven drying and solar drying. Thus, the all fifteen treatment combinations replicated thrice in factorial randomized block design. The chemical parameters under study were significantly varied with different pretreatments, drying methods and their interactions. Among drying methods, solar drying noticed comparatively better retention of reducing and non-reducing sugars, protein and also rehydration ratio as well as sensory score. Oven dried samples showed better retention of T.S.S. and ash only. Among different pretreatments, 0.25%KMS and 0.1%KMS+2%CaCl2 were found comparatively better for retention of T.S.S., non-reducing and total sugars and ascorbic acid. The sensory score was comparatively more in 0.25%KMS and 0.1%KMS+2%CaCl2 pretreated samples. With regards to interaction effects 0.25 per cent KMS pretreated samples followed by solar drying showed better results in most of the chemical parameters including sensory score. Thus, the pretreatment 0.25 % KMS as well as 0.1 % KMS+2 % CaCl2 followed by solar drying were found to be suitable for dehydration of white onion.