Ian McKeever, 42, died "doing what he loved best," his family said on his Facebook page, The Irish Times reported. The lightning strike injured several others in his group.
McKeever himself made a posting to Facebook a few hours before his death: Day 3 -- Shira 2, 4,000 meters (13,000 feet). Torrential rain all day. Spirits remain good even if drying clothes is proving impossible!
"We pray for drier weather tomorrow -- the big day. It's the Lava Tower," he wrote.
The climb was his second in less than a year up the highest mountain in Africa, The Irish Sun reported. In August, he led 145 people up the mountain in just over six days.
That trip raised money for Our Lady's Children's Hospital in Crumlin, Ireland, and the Chernobyl Children's Project.
McKeever had climbed all the Seven Summits, the seven highest mountains on the continents, a group that includes Mount Everest in Nepal, Mount McKinley in Alaska and the Vinson Massif in Antarctica.