The study's aim was to synthesize a crystalline film formed by L-threonine crystals complexed with Cu2+ ions (LTCu) dispersed in a galactomannan (Gal) solution as well as to characterize its structural, vibrational, and thermal properties. Gal(LTCu) films were prepared by the addition of copper II L-threoninate crystals in concentrations of 0.25, 0.50, and 0.75 in 2% Gal solution. To characterize the Gal(LTCu) properties, we used X-ray diffraction (XRD), UV-Vis and Raman spectroscopy, thermogravimetry, and thermal analyses (TG-DTA). XRD showed that the Gal(LTCu) films are crystalline and have acquired coloration similar to the one of LTCu crystal. The UV-Vis spectra revealed that the films tend to assume a square planar conformation due to Jahn Teller effect. Bands related to the interaction between the metal ion with the organic compounds were observed through the Raman spectra. TG-DTA showed that the films exhibit low thermal stability due to the dehydration process. POLYM. ENG. SCI., 2019. (c) 2019 Society of Plastics Engineers