Chitosan (CS) and poly(vinyl alcohol) (PVA) mixtures in acetic acid solution (AcAc) were investigated in order to determine the optimal composition required to design hydrogels in well-defined conditions. The main interest was to obtain materials which are in a liquid-like state at room temperature (injectable form) and transform into a gel at physiological temperature. CS/PVA mixtures with different compositions in 0.2% and 2% AcAc were investigated in dilute solution at 37 degrees C by viscometry. The intrinsic viscosity was evaluated by a classical method (Huggins equation) as well as by using a recent approach reported in literature (Wolf model). On the basis of miscibility parameter (triangle b) and refractive index values, the miscibility between CS and PVA was discussed. Mixtures with total polymer concentration between 3% and 10% and optimum polymer composition have been submitted to freezing/thawing cycles, and their rheological behavior was investigated. The viscoelastic properties of CS/PVA hydrogels depend on the polymer total concentration and the freezing/thawing cycles number. The gel state is reached at lower temperatures as the number of freezing/thawing cycles increases.