Naphthol Green B is a coordination complex of iron that is used as a dye.

The organic ligands each bind to iron as bidentate ligands through the nitrogen and the anionic phenoxide groups.

Naphthol Green B is used in histology to stain collagen.

[4] Moreover, it is used for polychrome stains with animal tissue.

For industry purposes Naphthol Green B is used for staining wool, nylon, paper, anoxidized aluminium and soap.