He said he was surprised that Mr Bolton would be allowed to "swim through the politest of polite soirees - which is of course Hay."
Mr Bolton, who was the American ambassador to the UN from August 2005 to January 2006, is due to talk at the Hay-on-Wye literary festival at 6.30pm on international relations.
Mr Monbiot, a columnist for The Guardian newspaper, plans to detain him as he steps off stage at the end of his talk. He said he was prepared to jump on stage and perform the citizen's arrest there if necessary.
He claimed Mr Bolton was "instrumental in preparing and initiating the Iraq war by disseminating false claims through the State Department" while he was under-secretary of state for arms control.
Mr Monbiot, who took part in a debate at Hay on Saturday entitled "Defeat: Why They Lost Iraq", has been a fierce critic of the decision to launch the 2003 invasion.
He said he had formally notified police of his intention of performing a citizen's arrest.
Mr Monbiot said: "This is the one opportunity we have, because he is mingling with the public, which doesn't happen very often."
He added: "I can't think of another case where someone who has been instrumental in planning the war has been exposed to the public, so I'm taking the opportunity.
"John Bolton was pushing for the Iraq war long before he became part of the administration."
Explaining his motivation for carrying out what will be a purely symbolic gesture, Mr Monbiot said: "Many people accept that the launching of the Iraq war was an international crime, but no one has yet been prepared to act on it by arresting one of the perpetrators."
Peter Florence, director of the Hay Festival, said Mr Monbiot's attempt at a citizen's arrest would be "completely unlawful".
He said: "The Hay Festival has sought the advice of both police and lawyers, and has been unequivocally assured that a citizen's arrest, or an attempt to instigate a citizen's arrest, would be completely unlawful in these circumstances.
"The Hay Festival remains committed to providing a platform for speakers from a diverse range of political and social backgrounds.
"However much we might take issue with a speaker's beliefs or opinions, we remain steadfast in our intention to provide them with a safe and free environment in which their views might be discussed with others.
"The Hay Festival encourages visitors to voice their opinions, but also requires that, in their expression, they respect both the law and the speaker."
© 2008 The Telegraph