Around 200,000 hopefuls from 140 countries initially signed up for the Mars One project, which is to be partly funded by a television reality show about the endeavour.
This has been whittled down to 100 people. After the five-day third phase of tests, it will be trimmed further to 40, of whom 24 will eventually be chosen for the one-way trips to the red planet, scheduled to start in 2026.
Mars One said the latest tests, 90 percent of which are those used by Nasa, will be done in teams.
"Over the course of five days, candidates will face various challenges," the Dutch-based non-profit organisation said in a statement.
"It will be the first time all candidates will meet in person and demonstrate their capabilities as a team.
"In this round the candidates will play an active role in decision making/group formation.
"Mars One has asked the candidates to group themselves into teams with the people they believe they can work well with."
As they will not be returning to Earth, those selected must be capable of living in small groups, finding water, producing oxygen and growing their own food.
Nasa is currently working on three Mars missions with the European Space Agency and plans to send another rover to Mars in 2020.
But Nasa plans for a manned mission to Mars are not until the 2030s.