[en] A particular K-Ar technique, the Cassignol technique, has been developed in order to date Upper Pleistocene and Holocene volcanic rocks. We describe here its principles and its technology. The limit of detectability of the radiogenic Ar portion corresponds to an error of less than 10³ a for K-rich minerals and a few 10³ a for basalts. The reliability of the results and the validity of the correction for atmospheric contamination have been checked by analysing historical lavas and by comparison with data obtained from radiocarbon and thermoluminescence dating methods. The results demonstrate that the technique is capable of achieving K-Ar dates as young as 2000 a with a few centuries accuracy. A precision of ± 1.5% is obtained for samples older than 10⁵ a. Moreover, in rocks older than 10⁷a, the technique permits the accurate dating of minute amounts of pure separated mineral phases. A reconstruction of the recent volcano-tectonic evolution of the Naples area has been carried out. It allows us to establish a model for estimating volcanic hazards in the Phlegrean Fields. The dated terrestrial pyroclastic deposits have been recovered from cores collected in the central Tyrrhenian Sea. The land-sea correlations allow us to refine the chronology of the marine oxygen isotope records for the past 60,000 a. 59 refs.; 7 figs.; 5 tabs