One-dimensional Co-doped titanate nanostructures with modified surface have been synthesized by alkaline hydrothermal method in the presence of bioactive natural polymer chitosan as the organic reagent. The properties of products as-prepared and annealed under atmospheric air conditions and vacuum were studied by Raman and IR spectroscopy, SEM, HRTEM, XRD, EDX, and magnetic analysis. The results show that numerous Co-containing agglomerates of chitosan derivatives are formed on the surface of one-dimensional nanostructures when chitosan added to the reaction system with CoTiO3 powder. An average cobalt concentration in surface formations is about 6.3 wt.% that is noticeably higher than in the body of layered structures. Magnetization measurements show a paramagnetic behavior for as-prepared products. After vacuum treatment at 600 degrees C and higher, the same nanostructures demonstrate the abnormal high ferromagnetic properties. Effect of chitosan as the organic reagent on texture, morphology, phase composition, and surface modification of nanostructured material is discussed. (C) 2014 Elsevier Ltd. All rights reserved.