Two laboratory experiments were conducted in spring 2023 to examine the effect of temperature on salt-induced flocculation of dissolved organic matter (DOM) in humic-rich river water. Water samples were collected from the Vantaanjoki River, Helsinki, Finland, and experiments were carried out at temperatures ranging from 3 ºC to 20 ºC. The formation of flocs was studied by measuring the quantity of suspended particulate material. The quality of DOM was measured by quantifying coloured DOM absorbance and fluorescence. The flocculation experiment was conducted as a jar experiment using Velp Scientifica FC6S flocculator (1 h at 60 RPM). Three treatments were applied: a salt treatment with the addition of saturated saline solution, a water treatment with ultrapure water, and a control treatment with filtered river water.