The complex of praseodymium with L. Tryptophan have been isolatel in solid state. The complex has the formula H3[Pr(Trp)3(NO3)3].2H2O. This complex reveal that L. Tryptophan acts as a neutral bidentate ligand towards Pr(III) ion at the presence of nitrate ion with utilizing amino nitrogen and carboxyloxygen for bonding.