The present Manual is on the biodiversity of freshwater algae of temple tanks of Kerala which is a special type of lentic ecosystem prevalent in several parts of South India. A total number 94 temple tanks were studied and 274 taxa of algae belonging to genera under chlorophyceae, Cyanophyceae, Bacillariophyceae, Euglenphyceae and other smaller groups of algae were recorded. Digital images of all the taxa are presented. The highlight of the manual is the information on the distribution of each species all over the country. This manual is an outcome of an effort to create a database on freshwater algae of India