Gąsocin [ɡɔ̃ˈsɔt͡ɕin] is a village in the administrative district of Gmina Sońsk, within Ciechanów County, Masovian Voivodeship, in east-central Poland. It lies approximately 5 kilometres (3 mi) south of Sońsk, 15 km (9 mi) south of Ciechanów, and 62 km (39 mi) north of Warsaw.