Marko Arnautovic's first-half strike separated the two sides as West Ham claimed a narrow victory in Wanderers' opening pre-season friendly at Adams Park.
A star-studded Hammers outfit began brightly and saw efforts from Robert Snodgrass and new signing Andriy Yarmolenko go close, while Scott Kashket headed wide at the other end from a Nathan Tyson cross.
Ryan Allsop denied Pablo Zabaleta with a smart stop before Arnautovic broke the deadlock before the interval, which saw Gareth Ainsworth make 11 changes to his side.
Then a trialist volleyed narrowly over and Adrian was called into action again to tip Anthony Stewart's header wide, before two late scrambles in the box were cleared by the Hammers as they held on to victory in their first game in the UK under Manuel Pellegrini's leadership.
Wycombe 1st Half: Allsop, Jombati, El-Abd, Trialist-CB1, Harriman, Trialist-LB, Saunders, Trialist-CM, O'Nien, Kashket, Tyson.
Wycombe 2nd Half: Ma-Kalambay, Jacobson, Gape, Stewart, Bean, Bloomfield, Cowan-Hall (Akinfenwa 75), Trialist-CB2, Thompson, Freeman, Trialist-CF.