Clear blends of chitosan acetate salt with poly (N-vinyl-2-pyrrolidone) (PVP) made from aqueous solutions look to be miscible on appearance. IR spectra investigated the carbonyl-hydroxyl hydrogen bonding between chain-chain in the blends and thus evidenced the compatibility of two polymers on a molecular level. The IR spectra, DSC also explored the interaction changing during the temperature increasing and indicated that a significant conformational change took place.