In the present study depositional temperature, diagenetic type and major climatic changes are investigated using oxygen and carbon stable isotopes. For this purpose, a sediment core (140 cm long) of 12 Km distance from the coast (near Langroud city), was collected from the southern Caspian Sea.A sedimentation rate of 0.9 cm/year was obtained based on a 210Pb and 137Cs isotope study of the sediment core. The depositional temperature and diagenetic type were obtained based on Mass Spectrometry analysis of sediment samples. The oxygen-carbon isotope study indicates a very low depth of burial diagenesis. Water temperature based on the heaviest oxygen isotope value with least alteration, shows around 21ºCduring sedimentation, (120 years ago) while CTD results during sampling show the same result, so it seems that there have been no major climatic changes in the study area.