Chlorogloea microcystoides is a species of cyanobacteria in the order Chroococcales, family Hyellaceae. Cyanobacteria are photosynthetic prokaryotes — often called blue-green algae though they are not true algae — that are among the most ecologically important organisms on Earth, responsible for a significant fraction of global oxygen production and nitrogen fixation. The genus Chlorogloea comprises colonial cyanobacteria that form irregular, gelatinous colonies where cells are embedded within a firm or soft mucilaginous matrix. These organisms occupy diverse aquatic and terrestrial habitats including freshwater lakes, wetlands, damp soils, and lithic (rock-surface) environments. The species name microcystoides suggests morphological similarity to the genus Microcystis, referring to the colony organisation. Like many colonial cyanobacteria, Chlorogloea species can produce bioactive compounds and contribute to primary production in their ecosystems. Under favourable conditions such as elevated temperature and nutrient availability, related cyanobacteria can form blooms in aquatic systems. As a microorganism, C. microcystoides has no common name and is classified as Not Evaluated by the IUCN. Taxonomic understanding of cyanobacterial species boundaries continues to evolve with molecular phylogenetic tools, and many genera are currently under revision as new sequence data illuminate true evolutionary relationships.