The European Open Science Cloud (EOSC) Partnership will bring together institutional, national and European initiatives and engage all relevant stakeholders to co-design and deploy a European Research Data Commons. The Partnership will seek engagement with the Member States and Associated Countries on two levels: i) via a “Steering Board” external to the EOSC Association; ii) and via mandated national organisations members of the EOSC Association. In addition to these official engagement mechanisms, a series of EOSC national structures have emerged in the last year with the goal of supporting the countries in organising the EOSC coordination and engagement activities at local level. The EOSC national structures do not necessarily correspond to the mandated organisations. In some countries, they are the first step towards the appointment of a mandated organisation but in many cases, they are complementary structures essential to bring EOSC closer to the national research community and to stimulate active participation of researchers as providers and users of FAIR digital content. This study, conducted by CSC – IT Center for Science in the context of the EOSCsecretariat.eu project has surveyed EOSC national structures in 24 EU Member States, 11 Associated Countries and Switzerland in 2021. The main findings of the study are summarised below: 83% of the surveyed countries have an EOSC national structure already in place or are in the process of setting up such a structure. At the time of writing the report only two EOSC national structures (Austria, Estonia) correspond to the mandated organisations of the EOSC Association; In 30% of the countries, the decision of setting up an EOSC national structure was a top-down decision coming from a ministry or a national research funding organisation whereas in 14% of the countries, EOSC national structure was pushed by researchers, Open Science stakeholders and other relevant actors in the country. In most cases, it was however the combination of the previous two approaches; The most common motivational mechanism triggering the set-up of the EOSC national structures is the need to coordinate the EOSC activities at national level to avoid duplication of efforts, align national views, strengthen collaborations at country level, define future investments and increase effects of individual efforts at European level; There are four ways how different countries have organised the EOSC structures at national level: i) Consortia; ii) Individual legal entities (in all the cases these are the predecessors of the national mandated organisations); iii) Expert Groups; iv) National Programmes. They have different governance structures, objectives and roles in the countries. An aspect common to all of them is that they are all striving for permanent structures; The four main priorities of the EOSC national structures are: i) Engaging stakeholders at national level into EOSC; ii) Coordinating EOSC activities at national level; iii) Disseminating EOSC at national level iv) Offering a channel to connect the national stakeholders with the EOSC governance. In some countries providing training on EOSC specific topics and steering and supporting national priorities and investments have also been indicated as crucial mandate of the EOSC national structure; The engagement and support of key national stakeholders, research funding organisations, policy makers and the government is considered an essential precondition for a successful establishment of the EOSC national structures. For their long term contribution to EOSC, their role needs to be clarified and recognized by the EOSC Partnership; The EOSC national structures can bring great added value to the countries by aligning efforts and improving the country position in EOSC; ensuring equal access to EOSC information and opportunities; increasing uptake of Open Science in the country; facilitating national networking and internationalisation opportunities. The EOSC national structures can support the EOSC Partnership in boosting the EOSC awareness and stakeholder engagement, overcoming language and cultural barriers, strengthening involvement of national policy makers and enforcing EOSC-compliant policies at national level and providing expertise to support the EOSC monitoring activities.