The examined portal is situated outdoors on the northern wall of the church transept. On a seriously destroyed sculpture ornament, only traces of polychromy have been preserved. Some 22 microsamples were taken for a complex chemical analysis. Six paint layers were identified, covered with a thick mortar-like deposit. When interpreting the experimental results, attempts were made to reconstruct the original coloring of the portal, changed by subsequent overpaintings. The earliest yellowish gray layer, adjacent to stone, consists of lead white, chalk and oil-water emulsion binder. It supposedly served as a mastic to equalize the stone coloring. This was covered by a red (red lead) oil layer. The third and fourth layers were similar to the first ones; they showed, however, a different composition. The fifth yellowish brown layer suggests a plaster preparation for gilding. The clearest distribution of paint is observed in a multicolor sixth layer. It contains, among others, smalt blue applied in European painting from the mid-16th to the beginning of the 19th centuries. Pigments identified in the earlier films were known and applied both in the Middle Ages and in the later centuries and are therefore not useful in dating these layers. The analyses show that in the earliest period the basic color of the portal was red. Investigation in progress on other Gothic stone portals originating from the same church may shed new light on these technological problems.