•Children represent a highly heterogeneous consumer group in the snack market.•Popular fast food branding has no positive influence on children’s snack choice.•Children’s price responsiveness is moderated by their cognitive abilities and age.•Higher prices could limit some children’s expenditures on less nutritious snacks.•Preferences and dislikes for a snack stimulate some children’s snack choice. The objective of the present study is to investigate the impact of brand and price on children’s purchase decisions in the snack market. It examines the role of nutritious snacks in children’s autonomous snack purchases and determines whether fast food branding can motivate the perception of rather nutritious snacks. It also considers child-specific characteristics to analyze the impact of brand and price on children’s purchase decisions. The study included an incentive-compatible purchase experiment with primary school children aged 7 to 10 years, a questionnaire, and a cognitive test measuring children’s context-related understanding of quantities. Three different food attributes were considered: snacks differing in healthiness, brand, and price. In the final analysis, 123 children were included. Data were analyzed using multinomial logit model, mixed logit model, and latent class analysis. The study highlights the heterogeneity of children as autonomous consumers in the snack market. Our results show that some children’s snack choice is positively influenced by their overall preferences for a snack option, and children’s price responsiveness is moderated by their cognitive abilities and age, while branding of a popular fast food brand has no positive influence on children’s (healthier) snack choices. We conclude that a multifaceted approach is required to encourage children to choose healthier snack options, including targeted price interventions (e.g. for older children) as well as measures that improve the quality and variety of healthier choices.