The chemical, functional and thermal properties of the mucilage from two phenotypes of chia seeds were investigated. In white and black-spotted seeds, the polysaccharides showed significant differences in total sugar content (between 78.9 +/- 2 % and 71.3 +/- 2 %, respectively) and in the nitrogen, carbon and oxygen content. Both polysaccharides were mainly composed of xylose, with arabinose, glucose, mannose and galactose in lower proportions, and there were significant differences in the levels of arabinose, galactose, glucuronic acid, mannose and xylose found between them. The mucilages from both phenotypes showed similar absorption bands in the Fourier transform infrared (FT-IR) spectra with small differences. The black mucilage showed a higher thermal stability at temperatures up to 287 degrees C. Finally, both polysaccharides showed a high solubility, high water absorption capacity and excellent water- and oil-holding capacities; therefore, both polysaccharides represent an excellent alternative for use as a functional ingredient in the food industry, regardless of the phenotype.