This is the first friendly confirmed by Athletic Bilbao for next season that will begin for Gaizka Garitano's team on July 4, the day the players are summoned to Lezama to begin training.
West Ham have been playing for two seasons at the London Stadium, the main venue for the 2012 Olympic Games, after leaving its historic Upton Park pitch in 2016.
Last season, under Chilean Manuel Pellegrini and with players like Pablo Zabaleta, Lucas Perez and Chicharito Hernandez in their ranks, the London team finished tenth in the English League.