Freshwater algae and cyanobacteria, their biodiversity in particular, have been studied at the James Ross Island (Antarctica) since 2004. The ma in aim of presented study was to contribute to species list of a particular seepage that has been monitored repeatedly on the northern deglaciated part of the Island. The seepage is located on north - facing slopes of Berry Hill and supplied by melt water fr om annual snow depositions and frozen ground . M icroclimate condition s ha ve been monitored by an automatic weather station since 2012. For the purpose of this study, samples of microbiological mats were col - lected from bottom of three streams passing throug h the seepage dominated by several moss species. Algal and cyanobacterial taxa were determined according to morpho - logical characteristics. Species richness differ ences between sampling sites were found and evaluated. Dominating taxa differed between sampl ing sites as well. The species reported in our study were compared with existing literature sources related to James Ross Island. Altogether, 44 algal and cyanobacterial taxa were found. Biodiversity of the seepage is discussed and related to microclimate characteristics of the site