Caçapava do Sul is a Brazilian municipality in the state of Rio Grande do Sul, located on the banks of the Camaquã River. As of 2006 the city had a population of 34,461. It was the 2nd capital of the Piratini Republic from 1839 to 1840.

The economy depends primarily on the mining industry. Caçapava do Sul produces 80% of the calcareous rock mined in Rio Grande do Sul. For many years it was Brazil's major producer of copper and is still an important center of copper mining.