Ross Underwood, 30, was last seen at HMP Springhill at Grendon Underwood on Sunday during 08:00 BST roll call.
Underwood is described as white, well built with green eyes and short cropped hair.
Police said the man, who has links to Northamptonshire and Leeds, "should not be approached directly".
Det Insp Joe Banfield, from Thames Valley Police, said: "We are keen to speak to anyone who may know the whereabouts of this man and can provide us with information about his movements."
A convict serving a seven year sentence for robbery has absconded from an open prison in Buckinghamshire "by unknown means", police said.