Former England and Surrey cricketer Adam Hollioake will travel from his home in Perth to run the London Marathon in memory of his brother Ben.
Ben Hollioake, also an England and Surrey cricketer, was 24 when he died in a road accident five years ago.
Adam is raising money for the Ben Hollioake Fund, which is collecting for the CHASE Hospice Care for Children.
"After retiring from professional cricket you'd think I'd be happy to put my feet up," said Hollioake.
"The Flora London Marathon could prove to be an even greater challenge, (with more blisters), than 'The Journey' in 2003 when we walked, cycled and rowed from Edinburgh to Morocco.
"However, with Ben in my thoughts and the support of the CHASE Cricket Runners, including Dad [John Hollioake], I will complete it.
"All the money raised will go towards creating a centre in South London that will enable expanded support for life limited children in Ben's memory."
Ben Hollioake died on 23 March 2002 in Perth, Australia, when he crashed his Porsche 968 into a wall.
Australian-born Adam Hollioake played four Tests and 35 one-day internationals for England, including 14 as captain, before retiring from cricket at the end of the 2004 season.