Oxalic acid dihydrate is used primarily as a cleaning agent for metal surfaces, especially in rust and oxide removal due to its ability to chelate iron. It is applied in the metal industry, particularly for iron and steel, to prepare surfaces for plating or coating. Additionally, it cleans electrodes and copper coils in the electrical and electronics manufacturing industries.

In the textile and paper industries, it serves as a bleaching agent for cotton fabrics and paper, removing yellow stains and embedded dirt to achieve whiteness.

Commonly applied in the restoration of antique furniture and wood surfaces to remove stains, bleach discoloration, and eliminate black or yellow marks from glue or moisture, preparing wood for repainting or varnishing.

Employed in beekeeping as a miticide against Varroa mites in honeybee colonies.

Also used in rare cases for polishing marble and other stone surfaces.

In households, it is found in descalers for removing limescale, mineral deposits, and rust from toilets, drains, sinks, bathroom counters, tools, and industrial equipment, particularly addressing yellow stains from hard water.