Police officers, ambulance staff and volunteers from the West Midlands region are to take on the three peaks challenge.
They hope to climb Ben Nevis in Scotland, Scafell Pike in England and Snowdon in Wales within 24 hours.
The team of ambulance service staff, St John Ambulance volunteers and West Mercia police are due to start the climb on Sunday.
Money raised during the initiative will go to several charities.
The group is set to begin the challenge on Ben Nevis at 1800 BST on Sunday.
They will then travel through the night to arrive at Scafell Pike at about 0400 BST and aim to leave the Lake District at about 0730 BST to arrive at Snowdon five hours later.
Training has been taking place for nearly nine months, West Midlands Ambulance Service said.