[3] Located in the northeastern part of the county, it borders the following townships: No municipalities are located in Colerain Township, although three unincorporated communities are located in the township: Portions of the unincorporated communities of Blaine and Lansing (a census-designated place) extend into Colerain Township.

It was named from Coleraine, in Northern Ireland.

[4] Statewide, other Colerain Townships are located in Hamilton and Ross counties.

The township is governed by a three-member board of trustees, who are elected in November of odd-numbered years to a four-year term beginning on the following January 1.

There is also an elected township fiscal officer,[5] who serves a four-year term beginning on April 1 of the year after the election, which is held in November of the year before the presidential election.