The special offer will run from 5 September to 16 October 2011 and covers 35 investment trusts offered on the platform.
The usual dealing fee of £12.50 will not be charged on the investment trusts within the range.
Alliance Trust said gross inflows into investment trusts through its i.nvest platform online had more than doubled from the 1 July to 31 August, compared to the same period last year.
Investment trusts offered by Aberdeen, Alliance Trust, Baillie Gifford and F&C, among other big-name investment houses, are included within the special offer.
