The sides will meet in Clonmel Celtic FC on Monday (3.00pm) and again on Wednesday (12.00pm) at Cahir Park AFC.
"It's our final two fixtures of the year so it's another opportunity for them to play a really high level opponent," said O'Brien.
"These games are always a great chance for our players to learn what is required to play against that a calibre of opponent which the Czech Republic normally prove to be.
"We've brought in a couple of new players so it's an opportunity for those players to learn about this level of the game while the players that were in before will hopefully build on what we've worked on with them throughout the season."
After two impressive performances against Poland in November, O'Brien's U15s travelled to a tournament in Turkey in February and produced some excellent displays against Netherlands, Turkey and Austria.
"We had an assessment day in March with 32 players but this will be the first time to work with the players since the tournament in February. We'll be focusing on the four functions of the game - attacking, defending and the transitions - both from a visual and practical point of view which will add to the players' knowledge," he added.
REPUBLIC OF IRELAND U15 SQUAD:
Adam Idah (Corinthians Boys)
Tyriek Wright (Lakewood)
Adam O'Reilly (Ringmahon Rangers)
Sean Brennan (Belvedere)
Jason Knight (Cabinteely)
Nathan Collins (Cherry Orchard)
Kevin O'Reilly (Cherry Orchard)
Seanie Mahon (Cherry Orchard)
Oisin McEntee (Malahide United)
Callum Thompson (St Joseph's Boys)
Max Murphy (St Joseph's Boys)
Kian Clarke (St Kevin's Boys)
Jamin Nwanze (St Kevin's Boys)
Kameron Ledwidge (St Kevin's Boys)
Ray O'Sullivan (St Kevin's Boys)
Marc Walsh (Gweedore Celtic)
Sam O'Gorman (Mervue United)
Hakeem Ryan (Mervue United)
Ciaran Brennan (East End Utd)
Barry Coffey (Nenagh AFC)
FIXTURES
U15 Friendly Internationals
Monday, April 11
Republic of Ireland v Czech Republic, Clonmel Celtic FC (3.00pm)
Wednesday, April 13
Republic of Ireland v Czech Republic, Cahir Park AFC (12.00pm)