Irish coach Sharon Boyle was delighted with her side who produced an excellent display against a side a year older.
After a tight first half, Heather Payne opened the scoring for Ireland three minutes into the second half when she cut in from the left and fired in a strike that the Welsh keeper failed to hold.
Emma Lawlor showed great pace to add Ireland's second goal in the 62nd minute as she raced through to slot past the advancing keeper.
Ireland went on to produce a dominant second half display with their defence holding firm to deny wales any significant clear cut chances.
The sides will meet again on Sunday afternoon.
"We did very well. Every player did their job and we were delighted with them. They did the work we asked them to do," said Boyle.
"We played the ball around very well. Megan Mackey our captain was a true leader and Tiegan Ruddy was also phenomenal at centre-back.
"The girls stood up really well against a strong side and particularly when you consider that they were giving away a year. We'll look to recover and see how we are for Sunday's game."
REPUBLIC OF IRELAND: Erica Turner, Harriet Lambe, Sadbh Doyle, Tiegan Ruddy, Tara Mannix, Heather Payne, Megan Mackey, Gillian Keenan, Aoife Fennell, Tara Cully, Carla McManus.
Subs: Lauryn Grier for Fennell, Aoife Lynagh for Ruddy, Sophie O’Donoghue for Mannix, Emma Lawlor for Cully, Hannah O’Donoghue for McManus, Rachel Baynes for Keenan, Doireann Fahey for Payne, Bethany Carroll for Lambe.