Professor Donaldson is a Professor in the Department of Physical and Environmental Sciences at U of T Scarborough and is a researcher in the areas of atmospheric, environmental and physical chemistry - using laser-induced fluorescence and Raman spectroscopies, non-linear laser spectroscopy, mass spectrometry, attenuated total reflectance FTIR and quantum chemical methods, combined with standard analytical methods (available in ANALEST) to probe and understand chemical interactions of atmospheric importance.

He is a Fellow of the American Association for the Advancement of Science, and a recipient of the U of T Scarborough's Principal's Research Award. He has held a number of administrative appointments, including tri-campus Associate Chair for Graduate Studies in the Department of Chemistry from 2008 to 2013, and Acting Chair of the Department of Physical and Environmental Sciences in 2018-19.