Kokšín, Nature reserve in Spálené Poříčí, Czech Republic.

Kokšín is a 20.63-hectare nature reserve on the slope of the 684-metre Kokšín hill in the Brdy range, about two kilometres east of Hořehledy. It protects flower-rich beech woods and fir-beech stands, with maple-beech forest on boulder slopes along its northern edge. The reserve lies at 592–673 metres and holds no watercourses.

Kokšín was first protected in 1955, when the Ministry of Culture of the Czechoslovak Republic set aside 2.25 hectares. In 1962 the area was enlarged to 18.39 hectares, and the present 20.63-hectare reserve was delimited in 1978 and formally established by Ministry of the Environment decree No. 6/1991. Since 2016 it has been part of the Brdy Protected Landscape Area.

The name Kokšín also denotes the 684 m hill above the reserve, whose summit holds the remains of a hillfort probably from the Hallstatt period; the fort lies at the southern edge of the reserve and outside it. Iron ore, and later radioactive ore, was mined on the slope, and traces of that mining remain in the reserve.

The reserve lies about two kilometres east of Hořehledy, roughly halfway towards Planiny, on the slope of the 684 m Kokšín hill; the reserve itself spans 592–673 m. There is no watercourse inside it, drainage runs via the Bradava and Mítovský potok. The hilltop with the hradiště remains lies outside the reserve boundary.

The summit of Kokšín hill, just outside the reserve boundary, was chosen as a site for studying stromatolites of the Czech Proterozoic. The reserve's metabasalt bedrock, grey-green and rich in iron ochres and hematite, also preserves traces of past iron-ore and radioactive-ore mining.