PurposeThe growing proportion of older fans and their potential economic value have increased the need for an improved understanding of age differences in fan behaviour. Building on socioemotional selectivity theory, the current study examines the impact of age differences on fan hatred as well as on the extent to which fans actually engage in aggressive activities and fans' perceptions of the levels of appropriateness of certain physical and verbal acts of aggression.Design/methodology/approachThe study used an online panel-based survey that offered access to a real-world population of sport fans. The participants were 742 fans of professional football (soccer).FindingsResults from structural equation modelling indicated that older fans reported lower levels of fan hatred, lower self-reported aggression and lower acceptance of physical and verbal aggression. Moreover, fan hatred partially mediated the relationship between age and levels of aggression and between age and acceptance of verbal aggression. In addition, fan hatred fully mediated the relationship between age and acceptance of physical aggression.Originality/valueThe current study makes two important contributions. First, it demonstrates that sport clubs may particularly benefit from understanding the potential but often neglected importance of older sport fans in relation to the problematic phenomenon of fan aggression. Second, it offers a thorough theoretical account of the manner in which fan hatred plays a significant role in the relationships between age and fan aggressiveness.