Biden mistakenly referred to a conversation he had with Merkel in 2021 as having taken place with Kohl, who died in 2017, on Wednesday night.
The 81-year-old president was speaking at a fundraiser in New York when he recalled a conversation from the G7 summit in 2021.
During the conversation, leaders had been talking about the January 6 attack on the US Capitol by Trump supporters, when the then-German leader Merkel spoke to the president.
Biden said: “When I first got elected president, I went to a G7 meeting with the seven heads of state in Europe and Great Britain. I sat down and I said, ‘Well, America’s back’ and the president of France looked at me and said, ‘for how long?' I never thought of it this way."
He then made the blunder: "Then Helmut Kohl of Germany looked at me and said, ‘What would you say Mr President, if you picked up the London Times tomorrow morning and learned that 1,000 people had broken down the doors, the doors of the British Parliament and killed some on the way in.'"
The White House had no immediate comment about the mix-up.
Earlier this week, while talking about the 2021 G7 summit, Biden mixed up French President Emmanuel Macron with the late Francois Mitterrand, who was in power from 1981 to 1995 and died in 1996.
Trump, 77, has misidentified people as well, recently confusing Republican opponent Nikki Haley with Nancy Pelosi, the California Democrat who was speaker of the House of Representatives when he was in power.