The aim of the present study was to examine the effects of consuming cereal bars, given either for breakfast or a mid-morning snack, on mood and memory. Thirty-two volunteers (16 males, 16 females; mean age, 20 years 9 months) were randomly assigned to one of four groups formed by combining breakfast (cereal bar versus no breakfast) and snack (cereal bar versus no snack) conditions. A baseline session was completed at 08:30 h followed by breakfast at 9:00 h, another test at 10:00 h, followed by a mid-morning snack and then a final test at 12:00 h. In each session, volunteers rated their mood and carried out four memory tasks: free recall; recognition memory; a verbal reasoning task; and a semantic processing task. The results showed that volunteers who consumed a cereal bar for breakfast felt more alert, happy and sociable and less anxious. In addition, they also recalled more words in a free recall task. When the cereal bar was consumed as a mid-morning snack, alertness and hedonic tone increased, especially in the group who received no breakfast. The group who had no breakfast reported reduced anxiety after consumption of the snack. Recall was also improved after the snack. These findings show that consuming cereal bars in the early and mid-morning leads to beneficial behavioural effects. The results confirm earlier research on effects of breakfast and extend our knowledge of effects of snacks. Consumption of cereal bars may have important practical applications especially in situations where preparation of breakfast is difficult.