Osieck [ˈɔɕɛt͡sk] is a town in Otwock County, Masovian Voivodeship, in east-central Poland. It is the seat of the gmina (administrative district) called Gmina Osieck.[1] It lies approximately 20 kilometres (12 mi) south-east of Otwock and 40 km (25 mi) south-east of Warsaw.
On 4 June 1981, a collision between two trains occurred near Osieck, killing 25 people.
Osieck was deprived of its town rights by the Tsar on June 1, 1869, which was a way to punish the city for the participation of its inhabitants in the January Uprising. On 1 January 2024 after 155 years Osieck regained its town rights.[2]