St Mary Hoo is a village and civil parish in Kent, England. It is on the Hoo Peninsula in the borough of Medway. According to the 2001 census it had a population of 244, falling to 238 at the 2011 Census. The first appearance of the name is in 1240. St Mary's Church at St Mary Hoo was the parish church and gave its name to the village, and although it remains a Grade II building, dating from the 14th century, it has been reconstructed as a private house.