Safranin O 0.5%, aqueous is an aqueous solution containing Safranin O dye at a concentration of 0.5%. Safranin O is a cationic dye commonly used in histology and microscopy for staining cell structures and tissues.

The main application of Safranin O is in the staining of cartilage, cell nuclei and glycosaminoglycans. It is often used as a counterstain in multistage staining protocols to highlight different structures within a tissue sample. A typical application is the use of Safranin O in trichrome staining, where it serves as a counterstain for staining collagen fibers.

The 0.5% aqueous solution allows for easy application and handling. The concentration is sufficient to provide effective staining without being excessive, which could result in non-specific staining. The aqueous solution provides good solubility and compatibility for most tissue samples and is a commonly used concentration for Safranin O staining.