Løvøya is an island in Porsgrunn Municipality in Telemark county, Norway.

The 0.25-square-kilometre (62-acre) island is located in the Ormerfjorden, just east of the island of Sandøya, and about 2 kilometres (1.2 mi) east of the town of Brevik.

In 1828, Morten Thrane Esmark found a black mineral on the island.

He sent it to Swedish chemist Jöns Jakob Berzelius for examination for further analysis.

Berzelius determined that it contained a new element, which he named thorium after Thor, the Norse god of thunder.