Introduction: This paper explores the characteristics of online museum visitors in an everyday life, information-seeking context. Method: A triangulation of research methods was applied. A Web questionnaire survey gave initial, quantitative information about online museum visitors to a military museum. Follow-up interviews (n = 24) obtained rich, qualitative data to validate and elaborate the characteristics of online museum visitors' information-seeking behaviour. Analysis: Based on the serious leisure perspective, data analysis led to the identification of two different user groups named collectors and liberal arts enthusiasts. Analysis showed that the two hobby classes have distinct profiles including differences in the nature of their knowledge acquisition. Results: Across the two hobby classes, participants can be characterised as special interest museum visitors pursuing a long-standing interest or hobby. The identified information needs were surprisingly well-defined known item needs and only few exploratory information needs were identified. Participants stressed the importance of personal channels and the social context of the hobby. Conclusions: The present study contributes to the research area of everyday life information seeking within serious leisure. It also contributes to the emerging field of museum informatics by adding to the characteristics of the online museum visitor.