The Institute of Material History of the Polish Academy of Science organized an archaeological excavation in Poznan Cathedral. Under the oldest part of the Cathedral several bishops graves were found. They date back to the 11th-13th centuries. Each grave contained a set of silver chalice, paten, and metallic crozier. The details are given about the technology and scientific examinations which were carried out after 1982, using several methods of chemical analysis such as atomic absorption, electron microscopy, microprobe analysis, etc. The conservation of the Romanesque and Gothic chalices and paten are also described. -- AATA