Climate activists who slept overnight in London's Science Museum will approach the attraction's visitors to tell them about its sponsorship deals.
A new gallery funded by a subsidiary of the Adani Group, a multinational business involved in coal extraction, is due to open in 2023.
About 30 members of the UK Student Climate Network (UKSCN) camped out in the lobby as a protest on behalf of "victims" of fossil fuel companies.
No arrests have been made.
Demonstrator Izzy Warren, 17, said the group, which includes school pupils, university students and scientists, chose to occupy the museum because the owners had ignored their petitions, letters and boycotts.
"We would really like to greet people who come to the museum this morning so they are aware of what they are supporting, and what they are paying for.
"The Science Museum is blatantly taking money from some of the worst perpetrators of the climate crisis."
The demonstration comes after the Science Museum last week announced a new gallery, called Energy Revolution: The Adani Green Energy Gallery.
Adani Green Energy is a solar power developer based in India and is a subsidiary of the Adani Group, which through another arm of its business is also involved in extracting coal.
A spokesperson for the renewables company said: "An environment where every child can grow up breathing pollution-free air - that is the environment we dream to create and have to a certain extent managed to enrich lives with our renewable energy plants.
"Adani Green Energy is pioneering in helping transition to renewable power generation. We develop, build, own, operate and maintain utility scale grid connected solar and wind projects."
Biologist Dr Alexander Penson, who took part in the sit-in, said it was "appalling" the museum was persisting in fossil fuel sponsorship and starting a new relationship with Adani.
The activists said they negotiated with museum staff to be moved from the second floor of the building to the Energy Hall near the main entrance so that they would have access to toilets for the whole night.
London's Science Museum
- The Science Museum is a major museum on Exhibition Road in South Kensington
- Founded in 1857, it is one of the city's major tourist attractions, attracting 3.3 million visitors every year
- It is free to enter, although special exhibitions may incur a fee
The museum has also faced criticism for partnering with Shell to fund its Our Future Planet exhibition, which is about carbon capture and storage and nature-based solutions to the climate crisis.
The agreement with the fossil fuel giant included a gagging clause, committing the museum not to say anything that could damage Shell's reputation.
The Science Museum has consistently defended its stance on working with fossil fuel partners.
Chief executive Ian Blatchford said trustees "are not convinced by the argument from some who say we should sever all ties with organisations that are 'tainted' by association, direct or indirect, with fossil fuels.
"We believe the right approach is to engage, debate and challenge companies, governments and individuals to do more to make the global economy less carbon intensive.
"Adani Green Energy is an example of an energy sector business bringing expertise and investment to renewables at the scale needed to deliver meaningful change."
A Met Police spokesperson said: "Officers attended and engaged with the protesters and museum staff.
"The protesters stated their intention was to remain in the museum overnight. This was agreed to by museum staff.
"No further police action was required."