Patrick Hatter, 34, absconded from HMP Springhill in Grendon Underwood sometime overnight between 11pm on Saturday and 7am on Sunday.
Hatter is white, around 5ft 11ins, skinny with muscular build, brown hair, brown eyes, clean shaven and he speaks with a London/Milton Keynes accent.
Det Insp Mark Baxter of Aylesbury CID 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.
“I would advise anyone who sees him to not approach him directly but to call police immediately.
“He has links in the Milton Keynes area and we expect he might have travelled to that part of the Thames Valley.
“I would like also like to remind people that it is a criminal offence to harbour an absconded prisoner and anyone found doing so is also risking arrest.”
Anyone with information about the location of Hatter should contact police via the 24-hour enquiry number 101 or call 999 in an emergency.
Alternatively, contact charity Crimestoppers anonymously on 0800 555 111.