ABSTRACT: In the area east of Gams (Styria, Austria), the Cretaceous/Paleogene boundary has been recognized in a newly discovered section, which comprises the upper part of the Cretaceous Nephrolithus frequens Zone (CC26) and the lower part of the Paleocene Markalius inversus Zone (NP1). The 6.5m long section is part of the Nierental Formation of the Gosau Group of the Northern Calcareous Alps. The boundary is characterized by (1) an enrichment of the contents of the siderophile elements Ir, Co, Ni, and Cr compared to the background and continental crustal values, (2) a sudden decrease of carbon and oxygen isotope values, (3) a sudden decrease of carbonate content, and (4) an acme of the calcareous dinoflagellate cyst Operculodinella operculata, which is succeeded by an acme of the small coccolith species Neobiscutum parvulum. The Neobiscutum acme is associated with a positive excursion of δ18O indicating a transient cooling of ocean surface waters due to short-lived changes in the configuration of ocean circulation after the impact.