Semi-empirical threshold fouling models predict higher fouling rates at high surface or film temperatures. Several experimental fouling data reported in literature and from our study were analyzed with respect to increase in surface and bulk temperatures that showed a decrease in fouling rates. The existing threshold fouling models do not adequately describe the phenomenon of decreasing fouling rates with increase in surface or bulk temperatures. The possible causes including the effect of temperature difference, heating regime and solubility of fouling precursors were analyzed and reported. © (2014) Trans Tech Publications, Switzerland.