Thermal tolerance is one of the most central traits that, in insects, correlate with distribution. With global temperatures projected to increase worldwide, much effort has been recently put into deciphering the physiological mechanisms constraining heat tolerance plasticity in ectotherms. However, we still know very little on how evolutionary pressures may have shaped physiological traits to enhance thermal tolerance in land insects. This is especially true in the case of mitochondrial functions, which have been repeatedly highlighted as central for ectotherms to survive exposition to non-optimal temperature regimes. Considering this central gap in our knowledge, we propose here to explore the mitochondrial adaptations associated with thermophily in insects, inside a consistent study system made of pairs of thermosensitive versus thermotolerant closely related ant species. Using this phylogenetic framework, we will (I) compare how temperatures affect specific steps along the mitochondrial Electron Transfer System (ETS) involved in respiration, (II) assess the impact of temperatures on mitochondrial ATP and ROS outputs, and (III) track adaptations in membrane composition and metabolic profiling associated with increased mitochondrial resilience to temperatures. Overall, this project thus proposes to explore important yet unanswered aspects of insect thermal biology that is located at the frontier of our current understanding of ecophysiology.