The effect of nepheline syenite on porosity soaking time relationship of porcelain stoneware bodies has been studied using the experimentally measured total porosity. A new kinetic model was applied to quantify porosity as function of temperature and soaking time. In the first part of work, the effect of nepheline syenite was evaluated on the kinetic parameters and the porosity variations were found to be related to surface tension/viscosity ratio of melted phase which influences the minimum porosity of ceramic body. The kinetic analysis of data indicated that the optimum soaking time to achieve minimum porosity in ceramic body is controlled by amount of nepheline syenite and milling time. The validity of presented theory to predict the experimental results was substantiated by computing total porosity at other temperatures and soaking times. The proposed model can be used to describe the sintering process of ceramic bodies that are sintered by diffusing melted phase. (C) 2010 Elsevier B.V. All rights reserved.