Rupert Haydock, national director of The Leprosy Mission England and Wales died suddenly on Wednesday, the charity has announced.
Haydock, 52, collapsed while at a Leprosy Mission supporters' meeting at a church in Langley Mill, Nottingham, and did not regain consciousness.
Haydock, who had been national director of The Leprosy Mission England and Wales since November 2007, had previously worked as an economist in the Falkland Islands for the Overseas Development Administration, and in community and organisational development for Tearfund in Burkina Faso.
Keith Nicholson, acting national director for the mission, said: "Mr Haydock was greatly respected, indeed loved, by his colleagues, family and all those who had the privilege of working with him. He was a wonderful and inspirational man.
"He will be greatly missed and mourned by The Leprosy Mission globally and all who ever met him."