In a context where the transition to less polluting transportation modes represents a major challenge in the fight against global warming, travel by rail appears as most likely to compete with travel by car for long-distance leisure travel for families. Then, it seems interesting to focus on the needs of a little considered public, but who can have an impact on present and future modal choices: the children. The scientific literature dealing with train travel time use proposes to rethink the value of travel time, which is key to the implementation of public transport policies. Assuming that transport time could be active and productive allows to reconsider the place given to speed in transportation projects (Mokhtarian, Salomon and Redmond, 2001; Ettema and Verschuren, 2007; Heywood et al., 2009; Molin et al., 2020). This field of research considers transportation modes as spaces of activity and proposes various time use typologies as framework for travel time use analysis (Lyons and Urry, 2005; Circella, Mokhtarian and Poff, 2012; Russell, 2012; Keseru and Macharis, 2018). In particular, they highlight how the growing ICT use multiplies the opportunities for activities on board (Adoue, 2016; Clayton, 2020). However, existing knowledge on train travel time use, primarily focuses on adults and especially on people travelling (regularly) for work purposes, as they represent more regular and more identifiable passengers. (Holley, Jain and Lyons, 2008; Gustafson, 2012). Children are therefore doubly excluded from this literature: since their train journeys are mostly occasional and for leisure purposes; and since they do not represent direct economic actors able to make their own modal choice (Depeau, 2013; Wood, 2016). They are only considered through their parents point of view (Price and Matthews, 2013), and the activity "take care of someone" (Lyons and Urry, 2005) in some travel time use typologies. Moreover, research on family trips concentrate mostly on car journeys (Chaim Noy, 2012). Furthermore, scientific literature on children mobility tends to focus on daily trips such as home-to-school journeys (Christensen et al., 2011) or issues about children independent mobility in public space (Fotel and Thomsen, 2003). Finally, the literature that considers children as actors and calls for a better consideration in public policies and public space design (Elsley, 2004; Wood, 2016), rarely considers mobile spaces such as trains. Yet, trains are found as space similar to urban spaces with a constrained context both from a spatio-temporal and social point of view (Fretigny, 2011). This research addresses the following questions. How does the analyses of time-use in trains by children lead to rethink the classical typologies of transport time use? What role do ICTs plays in train travel time use by children? In particular, do ICT help smoothing the spatio-temporal tensions related to (long) journeys in train ? This research is based on data collected using observations and interviews, that were considered more adapted to children than declarative surveys, that are commonly used in the studies in this field. Surveys were judged more difficult to administer because they rely on memory, and since they may suppose parental help. The observation method used was inspired by the work of Legendre and Depeau (2003) whose “behavioural cartography” allowed to analyse travel time use alongside with its spatial dimensions. Separate interviews were conducted with children observed during their train journey and their parents. The data used in this article represents about 80 hours of observations (108 children observed) and 26 people interviewed (12 parents, 14 children). Based on the observations, this article propose a travel time use typology for children travelling by train and compares it with the latest results available on adults train travel time use for leisure motives (Lyons, Jain and Weir, 2016), especially regarding the role of play and ICT use. Next, the impact of ICTs on children travel time use and the way its fits in travel time use agency and rhythm will be examined. Challenging the idea that ICT use is predominant in children travel time. Results such as relationship between travel time and ICT use, and intervention of ICT at precise times during travel will be presented. In a more qualitative approach, children discourses and drawings are analysed to understand how they consider ICT use in trains. Linked with parental discourses, and observations notes (including negotiation tools mobilised by children to access “screentime”), results display train travel as a space-time for opportunities and exceptions regarding daily activities.