‘Cool’ executive functions (EF) refer to logical and strategic cognitive processes such as planning and reasoning, whereas ‘hot’ EF include affect-driven cognitive processes, such as risk-taking in decision making. In the present crosssectional study was investigated whether prisoners perform worse than non-prisoners on measures of hot and cool EF. Subsequent objectives were to determine if performance on tasks of executive functioning was related to measures of (reactive and proactive) aggression within the offender group, and whether testosterone and cortisol influenced the latter relationship. Male prisoners (n = 125) and a non offender control group (n = 32) completed frequently applied measures of hot and cool EF (assessed with the Iowa Gambling task and Wisconsin Card Sorting Task respectively). Aggression characteristics in prisoners were assessed through self-report questionnaires, behavioural observations, and conviction histories. Endogenous testosterone and cortisol levels were obtained through saliva samples, while prenatal testosterone exposure was determined using the finger length of the index and ring fingers (the ‘2D:4D ratio’). The results indicated that prisoners performed significantly worse than non-prisoners on cool EF, and to a lesser extent on hot EF, but no meaningful relationship could be proven between measures of EF and aggression in the offender group. Weak to moderate significant correlations were found between testosterone/cortisol ratios (not prenatal testosterone exposure) and hot EF as well as self-reported aggression. These results lead to the conclusion that prisoners show significant problems in cool and hot EF compared to non-prisoners. These problems are not clearly associated with characteristics of aggression, but preliminary results indicate that these may be related to having high endogenous testosterone levels relative to cortisol levels.