SUMMARY: The results of a laboratory study carried out to investigate copper deposition and localized corrosion on API N-80 carbon steel are presented. Hydrochloric acid-based stimulation fluids and a recovered worn-out acid sample from the field were used in the tests. To all the tested fluids a copper-based corrosion inhibitor intensifier was added. The tests performed, which also included Scanning Electronic Microscopy and X-rays Fluorescence analysis, showed that the galvanic corrosion promoted by copper deposition on steel is evident and the corrosion process caused by the recovered worn-out acid might be severe.