Starting from an industrial body mix for porcelain stoneware tiles, part of its fluxing agent, sodium feldspar was replaced by a fine-grained microgranite. Sintering behaviour of the studied porcelain stoneware bodies with and without rnicrogranite was investigated using a double beam optical non-contact dilatometer according to the corresponding industrial firing profiles. The degree of vitrification of the densified samples and the other samples separately heated at different temperatures were determined by measuring the shrinkage, bulk density, water absorption and flexural strength. Furthermore, the colour measurements were carried out on the fired samples. X-ray diffraction (XRD) was used in order to analyze the phases formed after firing. In addition, scanning electron microscopy (SEM) was undertaken to observe the microstructural characteristics of fired bodies with respect to peak firing temperature. The results indicate that possible use of fine-grained microgranite as an effective fluxing agent in porcelain tile bodies.