After completing his thesis, he moved to the United States for a summer to work with Robert A. Alberty at the University of Wisconsin-Madison.
[7] A colleague from Cambridge, Tom Singer, had accepted a position at the Henry Ford Hospital in Detroit and recruited Massey to work with him to investigate the enzyme succinate dehydrogenase.
Massey was awarded the Henry Russel Lectureship in 1995, the highest recognition given to faculty members at the University of Michigan.
His major scientific contributions include the identification and kinetic characterization of lipoamide dehydrogenase[9] and pioneering the methods of stopped-flow[10] and rapid-freeze electron paramagnetic resonance (EPR) to study enzyme mechanisms.
[11] He published over 400 papers and at least an additional 50 book chapters, symposia or reviews, for example on artificial flavins as mechanistic probes.