On Saturday a group of about 100 campaigners, some carrying drums and banners, marched from the camp to the power station.
Most of the protesters returned to the camp in the afternoon apart from about 20 who created a human chain in front of the site's gates.
BBC correspondent Ben Ando, who spent most of the day at the Kingsnorth site, said: "The protest at the gates was good-natured and peaceful.
"A small hardcore - perhaps around 20 - staged a sit in by the gates and an hour later police officers moved in - arresting those who would not move and carrying them away. "
A spokeswoman for the Climate Camp claimed between 20 to 30 rafts had taken to the River Medway as part of the river protest.
Vow to return
She also said eight kayakers were detained by police when they got close to the station.
Ewa Steckel, one of the 1,500 campaigners who have been at the Climate Camp, said: "It's been great today, but a real victory for us will be when we have conclusively scuppered E.ON's coal-fuelled mania.
Assistant Chief Constable Gary Beautridge says a number of activists were arrested
"If Hutton gives the green light to this power plant, E.ON can expect to be seeing a lot more of us in the future."
The current Kingsnorth power station is due to close in 2015. E.On wants to replace it with two new coal units, which it claims will be 20% cleaner.
Its proposals, which would see the first new coal-fired power plant being built in the UK for 24 years, have already been approved by Medway Council but the government will make the final decision about the project.
The energy firm said the power station would provide energy for about 1.5 million homes and would be operational by 2012.
Activists have vowed to return to the power plant if the decision to build the new coal-fired station is approved.
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