Cyanobacteria are prokaryotic blue-green algae that are major constituent of planktonic communities in fresh water ecosystems.  Various forms of cyanobacteria occur in diverse habitats of Rajasthan. Many workers have explored the freshwater cyanobacteria of Rajasthan. During summer days cyanobacterial species flourish very well. Diversity of cyanobacteria in fresh water ecosystem under high temperature has been reported in this paper. For the identification of cyanobacterial species trinocular microscope was used.

Keywords: Freshwater, Diversity, Cyanobacteria.