Charles escaped to Boscobel in Shropshire in 1651
A rare "wanted" poster for Charles II is due to be auctioned in Shropshire next week.
The proclamation, dating back to 1651, is one of a number of Civil War documents being auctioned in Ludlow on 8 March.
Richard Westwood-Brookes, from Mullock's Auctioneers, said it had a guide price of £700 to £1,000.
The poster offers a reward of £1,000 for the capture of the king, who had escaped after the battle of Worcester.
Mr Westwood-Brookes said the money would be the equivalent of more than £75,000 today.
Issued by Oliver Cromwell's parliament, the proclamation calls for "the discovery and apprehending of Charles Stuart and other traitors, his adherents and abettors."
If he had been captured, Mr Westwood-Brookes said Charles would have almost certainly faced execution.
He added: "Had Charles been captured, it is most unlikely we would ever have returned to being a monarchy.
"In this year when we are celebrating the Diamond Jubilee of our Queen, it is worth remembering that the event would never be taking place if someone had been successful in collecting the reward."
After the execution of Charles I in 1649, his son raised an army to try to regain the throne.
After defeat to parliamentary forces at the Battle of Worcester, Charles fled to Shropshire, where he hid in an oak tree at Boscobel.
The monarchy was eventually restored with Charles II in 1661.