The 104-year-old scientist, who has travelled from Australia to Switzerland so he can end his life in an assisted suicide, has been pictured spending his last day in the garden.
Professor David Goodall gave a final press conference in the Swiss City of Basel on Wednesday.
‘At my age, or less than my age, one wants to be free to choose the death when the death is at an appropriate time,’ he said.
Prof Goodall’s abilities have been declining over the last two years and his eyesight has deteriorated.
‘I no longer want to continue life,’ he said. ‘I’m happy to have the chance tomorrow to end it.’
Prof Goodall spent his last day in the Botanical gardens in Basel alongside three of his grandchildren.
The botanist and ecologist, who has been a member of Exit International for 20 years, revealed he wants Beethoven’s 9th Symphony to be played as he is administered the drugs that will end his life at a clinic run by Life Cycle.
Prof Goodall was able to fly to Switzerland after Exit International raised more than £10,000 in a crowd funding appeal.
The law prevents him from ending his life in Australia.
Previously Prof Goodall said he believes people should be able to decide for themselves if they want to use medicine to die.
'I wouldn't suggest that it's available to everyone, and just going and buying it off the shelf,' he said.
'I think there are plenty of people who might misuse that. But I would accept that it should be done by doctors' prescription — but they should be free to prescribe.'
He will end his life at 10am on Thursday, local time, with family members by his side.