TWAS makes grants in support of conferences, workshops, symposia, and special meetings in developing countries. Requests are submitted by the organizers of the meetings (i.e., not by individual participants). Grants are intended for air tickets, and do not normally exceed US$5 thousand. Application deadlines are 01 June and 01 December each year.

Link: http://twas.ictp.it/prog/meetings/support-for-international-scientific-meetings