The goalkeeper is Palace's most-capped international while representing the club and holds the second-most appearances in Wales history (95), behind teammate Chris Gunter.
Gunter has also been picked for the European Championships this summer, alongside Palace Academy graduate Jonny Williams.
Hennessey, Gunter and Williams all featured in Wales' remarkable Euro 2016 tournament, in which the Red Dragons reached the tournament's semi-finals. They qualified for this year's competition for just the second time in history.
Hennessey could earn his 100th cap should he feature five times across Wales' two upcoming friendlies and enough Euro matches. He is rivalled by Leicester City's Danny Ward and Stoke City's Adam Davies in games against Switzerland (June 12th), Turkey (16th) and Italy (20th).
Best of luck, Wayne!