International research collaboration on decarbonization is needed if emissions reduction targets are to be achieved at the pace required and with lowest cost to all. While international exchanges on decarbonization still flourish amidst rising geopolitical challenges, whether these exchanges can result in effective collaboration remains unclear. This article reviews the current state and challenges, and proposes potential areas for international research collaboration on decarbonization. While countries are collaborating on research projects such as carbon capture, utilization and storage (CCUS), hydrogen, and materials development, collaboration mainly occurs as loosely coordinated activity between research groups, over relatively short time periods, at relatively modest scale, and still lack the degree of technical leadership and direction needed for effective delivery. These are due to multiple challenges in implementation and coordination, such as operation under different research systems, funding mechanisms and national priorities. This article perceives several opportunities for future international research collaboration on decarbonization, including disruptive technology innovations in different sectors, means for their efficient deployment at pace and scale, and policy planning on carbon budget.