Châtillon is a French commune of the department of Hauts-de-Seine in the region Île-de-France , southwest of Paris . Concerned by the perimeter of a nuclear installation, the municipality is a member of the local information commission with the CEA of Fontenay-aux-Roses . Country France Region Île-de-France Department Hauts-de-Seine Canton Châtillon Government  Mayor (2020–2026) Nadège Azzaz Area1 2.92 km2 (1.13 sq mi) Population (2017-01-01) 37,355 Time zone UTC+01:00 (CET)  Summer (DST) UTC+02:00 (CEST) Location  Châtillon borders in particular […]