Nano drug delivery has been recently used to improve the stability and bioavailability of drugs. The current work deal with the preparation and characterization of metformin loaded in chitosan nanoparticles (M-CHNPs) for medical purposes. Chitosan nanoparticles (CHNPs) were prepared by ionotropic gelation of chitosan with tripolyphosphate anions. Free chitosan nanoparticles and M-CHNPs were characterized via X-ray diffraction (XRD), dynamic light scattering (DLS), Raman spectrometer, high-resolution transmission electron microscopy (HRTEM), zeta sizing, BET surface area, and atomic force microscope (AFM). The drug encapsulation efficiency, drug loading capacity, and in vitro release rate were also investigated. ). The results showed that M-CHNPs were successfully prepared in pure form without any undesirable products as showed in X-ray diifraction pattern and Raman spectra. Also, the obtained M-CHNPs had an average hydrodynamic size of 78 nm, zeta potential of -28 mv, and showed a drug encapsulation efficiency and drug loading capacity up to 91%. In vitro release study indicated that metformin release from M-CHNPs was pH-dependent, where it released with rates 51%, 40%, and 10% pH 1.2, 6.8, and 7.4 respectively.