Apart from climate forcing, the hydrodynamic and thermal behaviour of lakes is determined by their morphology. In this communication we analyse the thermal characteristics of more than 400 French water bodies as a function of their size (depths from 1 m to 310 m, surfaces from 8·104 m2 to 6·108 m2, volumes from 1·105 m3 to 9·1010 m3). We use two data sources: 1) the Plan_deau data base, maintained by the French Agency for Biodiversity-Irstea research consortium at Aix-en-Provence and containing official monitoring data and lake morphological characteristics; 2) the LakeSST data set, containing surface temperature measurements derived from Landsat 5 and Landsat 7 thermal infrared images for 1999-2016. The results show the differential thermal characteristics of great lakes and may be used to group lakes in size classes according to their thermal behaviour.