Thermosensitive guar-based hydrogels are obtained in water solutions by copper-catalyzed 1,3-dipolar cycloaddition between alkyne-functionalized guars and alpha,omega-diazido-poly[(ethylene glycol)-co-(propylene glycol)]. Characterization by TGA, HR-MAS H-1 NMR, and rheology have shown that hydrogels with tunable physico-chemical properties, such as crosslinking density, viscoelasticity, swelling ratio, and so forth, could be obtained by varying the guar molar mass, the degree of alkyne functionality, the guar/crosslinker weight ratio, and the reaction temperature. Based on swelling measurements, it has been shown that the thermal sensitiveness of guar-based hydrogels is fast, reversible, and intimately related to the weight fraction of the thermosensitive crosslinker in the network. Finally, the monitoring of doxorubicin hydrochloride release has demonstrated the potential of these hydrogels as temperature-dependent drug release devices. The robust, efficient, and orthogonal approach described herein represents a general approach towards the development of well-controlled guar-based hydrogels using alpha,omega-diazido crosslinkers. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2733-2742, 2010