A pneumatic tube viscometer was used to study the apparent viscosity of seven different samples of processed Gouda cheese during processing in the temperature range 55-95 degreesC. Processed cheese has been behaved as a pseudoplastic fluid. Regression models were suggested in order to describe the effect of temperature and chemical composition on the rheological parameters. The flow behavior index was increased when the moisture content and the temperature were increased. Consistency index, and thus apparent viscosity, increased with reducing temperature and moisture content and increasing protein content. Fat was found to have no significant effect on the rheological behavior of processed cheese. The average activation energy of flow for all processed cheese samples was 15.85 kcal/mol. (C) 2003 Elsevier Ltd. All rights reserved.