The aim of this study is to determine the properties of metarhyolites from llgin-Konya (Turkey) area and to decide whether or not metarhyolites are suitable as a flux agent for porcelain stoneware tile production. For this aim, the chemical and mineralogical properties of metarhyolite were determined by chemical analyses, XRD and SEM studies. Starting from the reference mix composition, different amounts 4, 8, 12 and 16 wt.% of potassium feldspar were replaced with the same amounts of metarhyolite. All the samples were fired under industrial conditions at 1 200 °C for 49 min. The physical and mechanical properties of the fired porcelain stoneware bodies such as water absorption, linear shrinkage, bulk density and fired flexural strength were measured. Fired bodies were subjected to colour measurements and X-ray diffraction (XRD). The results indicate the possible use of metarhyolite as an effective fluxing agent in porcelain tile bodies.