In both child and adult populations, engagement in frequent physical activity results in a myriad of cognitive benefits, including improved executive functioning. However, the relationship between engagement in acute bouts of physical activity and cognitive processes, such as attention allocation, are less well understood. Methods: This study sought to: 1) Investigate the effects of an acute bout of exercise on behavioral responses; 2) Investigate the effects of an acute bout of exercise on neurophysiological measures; and, 3) Investigate age-related differential effects. EEG was recorded from 32 male participants (n=16 adults, n=16 children 9-11 years of age) who completed a 3-stimulus auditory oddball behavioral task, pre- and post-exercise intervention. Results: Contrary to expectations, this study found that, regardless of age, engagement in an acute bout of exercise did not have a significant effect upon some behavioral and all neurophysiological indices of attention, as measured by response accuracy, reaction time percent difference, and P3a and P3b amplitude, respectively. Moreover, the findings indicate no age-related differential effects of acute exercise on these same indices of attention. However, absolute reaction time results indicate a significant main effect for group (F (1, 21) =4.48, p<0.05) in the block immediately following the acute exercise intervention. Discussion: The relative ease with which both adult and child participants completed the behavioral task indicates that the task may have been simple, rather than executive in nature. Therefore, only some of the behavioral benefits and none of the typical neurophysiological benefits associated with acute exercise bouts were seen in this study, nor were age-related differential effects of acute exercise observed. However, the significant difference in reaction time between intervention and control groups immediately following the intervention, does provide the behavioral results typical of this intervention. Future studies should explore similar acute exercise interventions in combination with a varied behavioral task (e.g., a modified 3-stimulus auditory oddball) that strongly activates the executive functioning network.