It will be the first Sunday Heineken Cup final since the inaugural final in 1996 season when the reigning champions Toulouse beat Cardiff in extra time. It will also be a return to the scene of the 2000 Heineken Cup final when Northampton Saints pipped Munster 9-8 in front of a then record 68,441 crowd.
The Saints became only the second English team to lift European club rugby's most coveted trophy before Leicester Tigers' "double" in 2001 and 2002.
Announcing the news today (Tuesday, 2 December), ERC Chief Executive Derek McGrath said: "The ERC Board of Directors decided it would continue with the policy of the past two seasons in announcing the Heineken Cup final venue before the start of the campaign - so from today all roads lead to Twickenham.
"This gives all 24 teams in the tournament a specific goal and offers the fans a definitive venue as they follow their team's progress through the tournament.
"The Heineken Cup final is now established as a major European sporting event and it deserves and requires the investment of six months for us to build an event - it is a lot more than just a game - and reach the full potential of that event. Announcing the venue now is in the best interests of the Heineken Cup as it adds focus, value and incentive to the tournament and all its stake holders and partners.
"Celtic Warriors, one of the five new Welsh regional teams taking part in the Heineken Cup, will have the honour of kicking-off the event on Friday evening as we all set off on the 78-match road to the final Twickenham in just under six months time."
Tickets for the 2004 final will go on Wednesday, 3 December, 2003.
ERC will be putting an initial trench of 5,000 tickets on advance sale. Ticket prices start at £20 with top category tickets priced at £45.
You can purchase tickets by contacting Ticketmaster on their Heineken Cup Final hotline, 0870 161 1995 (UK number) or by logging on to www.ticketmaster.co.uk