This book constitutes the refereed post proceedings of the 18th Research Conference on Metadata and Semantic Research, MTSR 2024, held in Athens, Greece, during November 19–22, 2024.

The 23 full papers and 6 short papers included in this book were carefully reviewed and selected from 59 submissions. These papers were organized in the following sections: track on metadata, linked data, semantics and ontologies - general session; track on open repositories, research information systems & data infrastructures; track on digital libraries, information retrieval, big, linked, social & open data; track on cultural collections & application; track on european and national projects; and 8th dOAbLE - papers for libraries, archives,museums; track on agriculture, food & environment (agroSEM'24); track on digital humanities and digital curation.