Deputy Assistant Executive Director, United Nations Environment Programme since 1987. Director & Coord, 1982-1987, Deputy Director, 1974-1981, Environmental Management, United Nations Environment Programme, Kenya. Professor/Senior Lecturer, Department of Botany, University of Nairobi, 1969-1974.
Senior Lecturer/Lecturer, Department of Botany, Makerere University, Uganda, 6569. Rch Fellow, Purdue University, United States of America, 1963-1965.