Synthesis and Characterization of Photochromism Complex of 12-Molybdenum Phosporic Acid and Crystal Violet Jin Surong Tian Duoyu Xu Tian Lect.,School of Materials Science and Engineering,WUT,Wuhan 430070,China.Using 12 Molybodenum phosporic acid and crystal violet as raw material, the photochromism complex is synthesized and characterized by elemental analysis , X ray powder diffraction analysis,IR and UV Vis spectroscopy, TG DTA thermal analysis. The results show that crystal violet not do coordinate with heteropolyanion ,but with protons in heteropoly acid by coordination bond and the Keggin structure of complex do not change. Photochromism of complex undergoes electron transfer reaction on light to form multivalent molybdenum complex and accompanied by a color change from grin green to blue.photochromic; heteropoly complex; basic dyes