Another man is being treated in hospital for non life threatening injuries.
Gardai were alerted to a road crash on N4 in Moyvalley shortly after 2 o'clock this morning.
The crash involved two vans.
A man in his 60s, the driver of one of the vans, was pronounced dead at the scene.
His body has been removed to the mortuary at Naas General Hospital.
A man in his 30s, a passenger in the second van, was brought to Connolly Hospital in Dublin
He is being treated for injuries, which are understood to be non life threatening.
The road is currently closed for a technical examination and local diversions are in place.
Gardaí are appealing for witnesses to the crash to come forward.
And any road users with dashcam or video footage to make this available to them.
Anyone with information is asked to contact Leixlip Garda Station or the Garda Confidential Line.