The Taoiseach will be joined by Asimo, the walking, talking Honda robot in this evening's official opening of the Esat BT Young Scientist and Technology Exhibition.
The event now in its 40th year is hosting a record 482 entries involving 1,040 students.
The last of the student contestants arrived at the RDS venue in Ballsbridge, Dublin, this morning, to prepare their stands for formal judging, which got under way at 2 p.m.
The winning project will be announced by the Minister for Education and Science, Mr Dempsey, on Friday evening.
Along with being declared the Young Scientist of the Year, the winner will receive a cash prize of €3,000 and the chance to represent Ireland at the European Union Contest for Young Scientists.
There are four main categories; chemical, physical and mathematical sciences; the biological and ecological sciences; technology; and the social and behavioural sciences.
Aside from the top and runner-up prizes, dozens of awards and distinctions are given.
The exhibition ranks as the most important science awareness events of the year and promoters say it should encourage more students to take science subjects.
