A source familiar with the sale said there is strong interest for the bond, which is expected to be "comfortably oversubscribed", with bids collected as global markets open westwards.
Sri Lanka has been on a road show arranged by the Bank of America, HSBC Holdings and Royal Bank of Scotland group which is assisted by state-run Bank of Ceylon to sell the bond.
Fitch Ratings Monday gave a 'B+' rating with a 'positive' outlook for the bond. Fitch lifted the outlook on Sri Lanka's sovereign credit rating from 'stable' to 'positive' ahead of the bond sale and Standard & Poors' upgraded its rating to 'B+' from 'B'.
Moody's issued a 'B1' rating for the first time.
Agencies said the ratings could improve if the government improves is budgeting and the central bank keeps inflation low and the economy stable.
Sri Lanka's statistics office estimated economic growth at 8.5 percent for the second quarter and stocks are up over 100 percent so far this year.