A Laboratory experiment was conducted at Department of Seed Science and Technology, GKVK, UAS, Bangalore during 2013-14 to influence of accelerated ageing test on seed quality of onion (Allium cepa L.). The two genotypes of onion hybrid Kirthiman and variety Arkha kalyan seeds subjected to the accelerated ageing at 45±2⁰C for 100% RH for various time intervals (0,1,2,3,4,5,6,7,8,9,10 days) and seed quality tests of the seed material completed (germination percentage, shoot length, root length, mean seedling length, mean seedling dry weight, seedling vigor index, electrical conductivity and total dehyadrogenase activity), before and after ageing treatments. The seed showed a gradual and sequential reduction in germination percentage and seedling vigour as accelerated ageing duration increased. Seed leachate conductivity increased with ageing duration.