Lauri Halonen obtained his PhD in 1980 with Ian Mills in the University of Reading, UK. He has worked altogether about 11 years abroad. This includes the doctoral work in Reading, and the time in the University of Oxford, ETH Zürich, University of Princeton, JILA (Boulder Colorado), University College London, University of Copenhagen and Université Paris Est (Marne-la-Vallée). He became full professor of Physical Chemistry in 1992 in the University of Helsinki. He was elected as a member in the Finnish Academy of Science and Letters and a corresponding member in Akademie der Wissenscaften zu Göttingen.

He has worked in computational, theoretical and experimental science areas, particularly in spectroscopy and dynamics. He has supervised 24 graduate students including the youngest doctor (20 years old) during the history of independent Finland. He has taken part in 5 COST networks as a management committee member.