The synthesis and characterization of chitosan (CS) nanoparticles used as drug carrier was reported. The formation of nanoparticles, taking place in an aqueous phase without using auxiliary toxic substances via the ionic interaction between NH3 + protonated group of CS and phosphate group of sodium tripolyphosphate (TPP) was monitored in situ by combined UV-vis and pH measurements. The synthesized nanoparticles were characterized by TGA/DTA, XRD and TEM. The particle size, estimated by TEM, was found around 50 - 70 nm, with a quite uniform size distribution.
