Paleocorrosion, a new domain in science of materials, refers to the understanding of the processes of degradation of the “ancient” metal materials. Objectives are to decipher technical, ethnological or simply historic information inherent in them. It is not only a question of allowing their reading, but also to estimate their state of degradation to ensure their durability. The understanding of the deteriorated structures requires physical chemical characterizations (analytical, structural or even functional), often with a high level of performance, according to a very particular approach. The main methods of investigation to study these problems are presented and illustrated with some specific archaeological samples.