In the present work, Ovalbumin and beta-lactoglobulin fouling phenomenon was studied, when white egg and milk flowed in the inner tube of a double tube heated by hot water which flows in the ring space between them. The fouling kinetics depends on the mass transfer effects, which is a function of protein solubility. To describe the fouling kinetics a calculus algorithm was developed, having as subsidy the protein solubility itself. The proteins solubility curves have been taken by previous works. Results showed that ovalbumin fouling was slower than beta-lactoglobulin and the time necessary for the tube's inner radius to decrease in 30% of the original radius was smaller for high temperatures, for both proteins. Besides, both ovalburnin and beta-lactoglobulin deposition was greater at the tube's entrance than in its exit. Therefore, the radius reduction was faster in that area. (c) 2005 Elsevier Ltd. All rights reserved.