-The settling of diatoms as fouling organisms on a certain substrate is greatly infl uenced by substrate characteristics and the preferences of a diatom community and diatom species. A distinction among substrates can be made by analysing the specifi c abundance and composition of diatoms on different substrates. In this study, 11 different artificial substrates were exposed to a marine environment for a period of 30 days. Abundance and taxonomic composition of periphytic diatoms was determined on each of the substrates and on shoots of the marine seagrass Posidonia oceanica. The aim was to compare diatom community structure on different newly colonized surfaces. On all surfaces examined, periphytic diatoms were the pioneering organisms with differences in quantitative and qualitative composition on the different substrates. Taxonomic analysis of diatom communities on the substrates examined revealed 41 diatom taxa, with the dominant genera Cylindrotheca, Amphora, Nitzschia, Cocconeis and Navicula. Given that all the examined artifi cial substrates were solid materials, differences in the abundance and species composition of diatoms found between the materials point to the substrates' physical and chemical characteristics as a major infl uence on the fi nal settling of diatoms. Knowledge from investigating the settlement of fouling organisms on anthropogenic substrates can have future use in management of waste materials that end up in the marine environment.