| University of Kinshasa, D.R Congo | Junior Lecturer | October 1978 – October 1979 |
| University of Louvain, Belgium | Research Assistant | November 1979 – May 1985 |
| University of Annaba, Algeria | Lecturer and Senior Lecturer (from January 1988) | November 1985 – January 1989 |
| International Centre for Theoretical Physics, Italy | Postdoctoral Fellow | February 1989 – July 1991 |
| University of Kinshasa, D.R Congo | Associate Professor and Professor (from January 1996) | September 1991 – April 1996 |
| Vista University, Mamelodi Campus, South Africa | Senior Lecturer, Associate Professor (from October 1996) and Professor (from October 1997) | May 1996 – 30 November 2000 |
| University of Pretoria, South Africa | Professor Chairperson: School of Mathematical Sciences | 1 December 2000 –present 1 January 2005 – 30 November 2009 |
| University of Pretoria, South Africa | Head: Department of Mathematics and Applied Mathematics | 1 May 2004 – 31 July 2013 |
| University of Pretoria, South Africa | SARChI Chair in Mathematical Models and Methods in Bioengineering and Biosciences | 1 August 2013- 15 March 2015 |
| University of Pretoria, South Africa | Dean: Faculty of Natural and Agricultural Sciences | 15 March 2015 - 30 September 2019 |
| University of Pretoria, South Africa | Emeritus Professor: Department of Mathematics and Applied Mathematics | 1 October 2019 - current |
| University of the Witwatersrand, Johannesburg | Distinguished Professor: School of Computer Science and Applied Mathematics | 1 January 2022 - current |
