Kołacin [kɔˈwat͡ɕin] is a village in the administrative district of Gmina Książ Wielkopolski, within Śrem County, Greater Poland Voivodeship, in west-central Poland. It lies approximately 8 kilometres (5 mi) south of Książ Wielkopolski, 20 km (12 mi) south-east of Śrem, and 51 km (32 mi) south-east of the regional capital Poznań.