Satellite images acquired in the thermal infrared part of electromagnetic spectrum are often used in studies of environmental changes, including the phenomenon of an urban heat island effect.. The first part of this master thesis deals with theoretical background of land surface temperature determination from Landsat satellite images. Factors that affect the electromagnetic waves in the thermal part of spectrum and methods that allow their determination or assessment are described. Algorithms and their accuracy for determination of land surface temperature from Landsat images are presented in detail. The second part describes the study of an urban heat island in Ljubljana. Data from Landsat 8 was used primarily, but we also included Landsat 5 and 7 images. This enabled a chronological overview of land surface temperature in Ljubljana. Results confirm the presence of the urban heat
island and highlight the often overheated areas in the city.