The excavation at Iznik tiles kilns continues as the third period of the field mission. We present here the first on site, non-invasive analyses performed with portable XRF instrument on twenty-five excavated tiles and two residue materials of the kiln. The shards studied were attributed to the productions from 14th- to 17th-centuries. The comparison was made by the discussion of characteristic elemental ratios selected from the ceramic technology criteria and PCA/Euclidean distances analysis. Three groups of body and glaze technologies were evidenced. We encountered that the amount of tin oxide in the glaze decreased over the centuries. Besides, two different types of fluxes were used in the glaze, some containing only potassium, and the others having potassium and calcium. The decors, which were investigated in this study were blue, turquoise, green, red colours, and black lines. A copper-iron mixture in the red areas was documented, which reflects the use of bornite.