Poly crystals of pure thiourea doped with L-valine an organic material: have beengrown by slow evaporation technique at room temperature .The crystalline nature of growncrystal was confirmed by power x ray diffraction analysis (XRD).The functional group of thegrown crystals was found by FTIR analysis. The spectral bands have been compared withsimilar thiourea complexes using FTIR spectrum in the range 1000- 3500 cm-1 .The UV- Visstudy was performed to know optical behaviour of the grown crystals.