The article provides information on the diversity of algae and cyanoprokaryotes colonizing the ash dump of the Apatity cogeneration plant. The study area is located in the Belaya
River valley in the Khibiny Mountains (Murmansk Region). The species composition of algae was studied by means of culture techniques. The data for all samples were fed into the CYANOpro information system. A total of 85 taxa of eukaryotic algae and 10 cyanoprokaryotes were observed. Excentrochloris fraunhoferiana, Sarcinofilum mucosum, Podohedra bicaudata, Hormidiella parvula, and Streptosarcina costaricana are reported for the first time for Russia. A floristic comparison of the species composition of three different localities is provided. The temporal distribution of algae and cyanoprokaryotes indicates that the late stage of overgrowing of the ash dump is more similar to the natural species composition of north-taiga forest soils. Filamentous green algae and cyanoprokaryotes had a high occurrence. These strains could potentially be used for remediation of the technogenic substrates.