In 2016, the European Commission gave EFSA a mandate to update its 2009 opinion on the appropriate age for introduction of complementary feeding of infants. In order to retrieve data on health outcomes related to the age of introduction of complementary food, a systematic literature review will be conducted by EFSA. This report presents the preparatory work that is performed by Pallas, with advice of Wageningen University, for the systematic literature review. It provides an overview of references of eligible studies and grey literature documents describing or investigating the age for introduction of complementary feeding in relation to health outcomes. To collect these, an extensive literature search was performed for peer‐reviewed literature in three databases (PubMed, Web of Science and the Cochrane Library), according to the EFSA guidance document. After the execution of the searches, references found were screened by a two‐stage selection procedure: (1) Title and abstract screening; (2) Full‐text assessment of eligible references identified during the previous step. In both steps, 100% of the references were assessed in duplicate by two independent reviewers. Discrepancies in selected references were solved consensus based, or when necessary, discussed with a third reviewer. In addition, a grey literature search was executed in appropriate sources (NTIS, Open Grey, CAB Abstracts and Open Access Theses and Dissertations). From the literature search, 184 references were considered eligible, including 36 resulting from the hand search. An additional 30 references resulted from the grey‐literature search. All pertinent peer‐reviewed studies are listed in tables, categorised by type of health outcome and with data source. Also, an overview of non‐pertinent studies is presented with data source and reason for exclusion in the appendix. Relevant grey data sources are listed in a separate table. Along with this report, two Endnote libraries are delivered; one library with all studies considered pertinent and a second library comprising all excluded references. Finally, a few issues that can be taken into consideration during the further execution of the systematic literature review (risk of bias assessment, data extraction and reporting) are discussed in this report.