Murray Badger is an acknowledged international leader of research into photosynthetic CO2 acquisition and metabolism in aquatic and terrestrial organisms. His distinctive early contributions defined the activation mechanism and conditions for measurement of CO2 fixation and O2 uptake by ribulose bisphosphate carboxylase-oxygenase (Rubisco). He is acclaimed for discovery of CO2 concentrating mechanisms (CCMs) in cyanobacteria and algae. These minimize O2 inhibition of CO2 fixation and thereby unmask the co-evolution of Rubisco kinetics and diversity of CCMs, from cyanobacteria to higher plants. His research is typified by integrated, innovative approaches that have greatly facilitated molecular, genomic and functional characterization of systems from the cyanobacterial CCM to rate limitations of photosynthesis in higher plants.