Hundreds of students will be vying for the top prize when the BT Young Scientist and Technology Exhibition opens today at the RDS in Dublin.
The opening ceremony will see President Mary McAleese join forces with an eight-foot-tall robot called Titan who can talk and move about.
An estimated 35,000 people are expected to attend the fair over the next three days.
Judging of the projects, which have been whittled down to 500 from an 1,152 initial entries from 2,500 students, begins this afternoon.
The final awards are to be presented by Minister for Education Mary Hanafin on Friday night.
There is a prize fund of €5,000 available for the winning projects. In addition, there are also a number of special awards, including travel and the opportunity to take part in the EU's young scientist exhibition next autumn.