Abstract: Various kinds of hydrophilic monomers (such as methacrylic acid and acrylamide) were grafted in the vapor phase onto polypropylene plate (1mm thickness) by photo-grafting in the presence of benzophenone as a photosensitizer. The hydrophobic surface of polypropylene plate was modified to a hydrophilic one by photografting. ESCA and the water contact angle measurements confirmed that the graft polymerization occu-red on the plate surface. Certain water-soluble dyes (crystal violet and rhodamine B) showed a strong affinity for the grafted surface.