Open Government Data (OGD) has been globally promoted as a transformative tool for transparency, governance, economic growth and technological innovation, among other benefits. This one-way direction of influence assumes that OGD has the potential to intervene in political institutions and reshape dominant politics in the public sector; aspects that have dominated the OGD research and advocacy arenas during the past years. Despite this potentially transformative role, literature suggests that OGD initiatives are also embedded in dominant and long-term political institutions. OGD intervenes in political spaces and is framed by specific bureaucratic practices and regulatory bodies. OGD disclosure also interferes in distribution of power and personal interests derived from the management of public datasets. Hence, to fully understand and implement OGD it is necessary to study the opposite direction of influence: how political institutions and power shape the design, implementation and operation of OGD initiatives. This research gap constitutes the main aim to be fulfilled by this work. Two theoretical approaches are adopted in this work to elucidate this causality relationship, and which are suitable to understand the politics of digital initiatives: Historical Institutionalism (operationalised through Path Dependence analysis) is selected to understand the influence of long-term historical political institutions on OGD, and is complemented by a self-developed institutionalisation model based on institutional features; and the Circuits of Power theory is used to comprehend the influence of the exertion of power among direct stakeholders involved in the development of OGD in the public sector. These two models constitute the theoretical basis of this qualitative study on the Chilean OGD programme, with findings that provide significant new insights to understand the "politicalness" of OGD. The first aspect of study is how political institutions influence the development of OGD. Three historical political institutions shape OGD development: digital government, transparency and access to public information, and public data governance institutions. Evidence suggests that OGD follows fairly similar institutional trajectories to those historical institutions, and reproduces their dominant symbolic institutional features related to: using ICTs to project an image of modernity and efficiency, politicising ICT-based initiatives, and promoting short-term initiatives rather than long-term policies. The consequences of this scenario are that OGD has remained weakly institutionalised, and the initiative largely reinforces the institutions it attempts to transform. The second area of study is how the exertion of power between the leading unit and sectoral publishers influences the development of OGD. Evidence suggests that the leading unit does not have sufficient authority and legitimacy to impose OGD, given the limited standing conditions it holds. Within this context, the leading unit cannot create collective goals around OGD nor embed data disclosure within working practices and routines. As a result, sectoral agencies exert power resistance to OGD disclosure, which leads to a limited institutionalisation of this initiative and diverse levels of compliance and engagement from sectoral agencies participating in OGD. All in all, this work contributes to the body of knowledge in several aspects. Methodologically, it integrates two relevant political theoretical frameworks within the study of OGD and wider digital technologies. This work also provides a novel institutionalisation model for OGD based on the level of symbolism and materialism of key institutional features, as well as incentives and resources required in this process, and which can be applicable in other contexts. This research also expands the political understanding and empirical work of OGD by underscoring that OGD initiatives are highly dependent on the institutions and agents that intervene in its development. It is thus crucial that these actors are taken into account at the time of designing and implementing OGD initiatives. This analysis concludes that an adequate institutionalisation process is required if OGD is expected to deliver positive outcomes.