The influence of EU Framework Programmes on European and even global research policies is increasing every year. One of the examples of this trend is the fast development of research impact evaluation. In particular, this concerns studies that are dealing with long-term effects of R&D funding programmes. Bibliometric data have been one type of indicators of research funding. In case of EU Framework Programmes there are numerous questions and options as to a) the choice of reliable data sources, b) compatibility of different datasets, c) reliability of referencing practices, d) time consuming data cleaning, e) the additional workload due to the overlap between the various framework programmes (if the goal is to make a survey on the results of a specific framework programme). The objective of the current paper is to analyse, using the example of the FPs, to what extent the existing sources of information (WoS) make it possible to form an adequate picture of the impact of FP funding, and what are the shortcomings. A characteristic feature of FPs is their long-term durability, both in terms of signed contracts and in terms of the output timeline. The peak of the publication is reached eight to nine years after the start of the Framework Programme. Despite the clear referencing rules, grant recipients are not following them. The reliability of data is becoming a key issue.