The Die Hard star will auction five motorbikes from his personal collection, including a 1972 Harley Davidson Ironhead Sportster XLH and a 2005 Ducati 1000DS with only 285 miles (459 kilometres) clocked up.
The actor, who was born on a German military base, admits he is thrilled to support the U.S. Forces by donating proceeds to the Boot Campaign, a non-profit military appreciation organisation.
He says, ""I wanted to use my bikes in a way that would benefit our military service members, and I am thankful to have found the Boot Campaign as the catalyst for using my bikes in a way that will give back to our country's true heroes.
""These bikes have been a lot of fun to ride, and my hope is they can do a lot of good for our veterans.""
Willis will release one motorcycle every two months to be sold on Internet auction site CharityBuzz.com.