Femöre battery (also known as "Battery OD") is a facility previously operated by the coastal artillery arm of Swedish armed forces. It is located only a short trip south-east of Oxelösund on the Swedish east coast, and is blasted into the rock on the Femöre peninsula. The facility totals approx. 3300m² in size, and is connected via a over 450 meter long tunnel, stretching across the length of the facility.
The battery was part of a series of similar facilities built during the 1960s and 70's as a defence against potential attacks from the Soviet Union. Battery OD was the third of a total of 30 forts built in Sweden during the cold war.
The Femöre battery was decommissioned in 1997, and was scheduled for dismantling in 2003. Due to a local interest group, the large parts of the fort was instead preserved, and is today used as a museum. Since 2003, the battery has been open for regular tours, during the summer.
The armament consisted of 3 7.5 cm tornpjäs m/57, with an effective range of 13 kilometres.