Protesters clashed with police Tuesday during a march in support of striking metalworkers.
Stones and bottles were thrown at the police who responded with baton charges and the firing of low velocity exploding rounds.
Metalworkers have been striking for over 8 days in an attempt to improve their pay conditions.
Talks held overnight failed.
The metalworkers are closely linked to the ship building and repair industry in and around the port of Cadiz.